I can, to some extent at least, understand your stated concern. I have some familiarity at least with your background and friendship with wolfgirlcoven. It is not uncommon for people with delusion to be victims of abuse, I have faced it myself, though not directly relating to therianthropy but from my isolation.
I think there are a couple key things to discuss here that will build upon each other.
Firstly, where and how exactly do we define delusion. Delusion is something that is very culturally defined, and different areas have different lines of delusion. In therian community, many would consider my experiences as CLCZ delusion even if to me they are incredibly real (though this is also essentially the functional definition of delusion). On your blog you mention identifying with terms therian and otherkind, to broader society they may well label you as delusional though I expect you would reject such a label. We should collectively agree trans people are not delusional, though it is one of the most common clichés thrown at trans people by reactionaries. I used to hear spirits, and for this I was marked delusional. Many christians would mark me as delusional for my belief in spirits and hallucinating hearing their voices. Yet many believe in angels visiting people, or that a rich man hears the voice of god telling them to run for most often the presidency of the US. A hardline atheist would likely mark both myself and the christians for our belief in such spirits and gods. And though it may seem hard to believe, there are cultures where experiences like I have are not considered delusion. The idea of cultural relativism is so important it is baked into the diagnostic criteria of many conditions.
At the moment you presumably find yourself on the "sane" side of that line of acceptability - it is very easy to believe the structure of the world you exist within is natural and logical and sensible, especially if you lie on the "acceptable" side of that line. People in current times believe very heavily in rationalism, or believe they believe in rationalism. Few people at least where I live, will claim that we should do X or Y because god wills it, even even those that do attempt to put forth some sort of scientific or rational explanation for their beliefs. It is very common for right wingers to advertise themselves as rational and logical when parroting "common sense" which are the prevailing cultural narratives within a time period, even if scientific understanding has moved on from those narratives. However, that line of delusion versus sane is ever shifting, ever moving, I doubt I will ever lie on the "sane" side of that line, but that line is far from carved into stone.
Secondly, there have been abusive cults in the past particularly among the P-shifter community. I do not think that is controversial to say (though I am told they are taking steps to manage the problem of bad actors and cults). I do not interact with the P-shifter community very much, either currently nor in the past, however my experience within the therian community has been heavily affected by the presence of those cults and abuses. I can understand why communities would engage caution, however the result for me was often isolation or exclusion from the community which is supposed to be my own, and even where I was tolerated, was to always make sure that they knew that I knew my experience was delusion and was not real in the same ways as other therians were. Though I tag my posts with therian, to be honest I don't relate to the label, it took me years to feel comfortable to call myself therian, but still more and more I do not think I will ever be really accepted by the community and will always be an outsider. I did not hurt anyone, I have no connection to the P-shifter cults that hurt your friend or any other people. But still because of condition I have I have to bear the problems of this other group. Even among those who tolerate CLCZ or why we are okay within the community, our accepting of being delusional is why we can be tolerated. Why should people like myself hurt for the actions of a few bad individuals?
Beyond that though, I do not think those with delusions are any more susceptible to the various cults than non delusional people, or at least not uniquely susceptible. What makes those groups possibly alluring to those with delusion is not those promises of transformation, but the hope of understanding and community (I will move on for the moment but this will be important later). For those without delusion of transformation, it is that promise that you can transform, that promise that if you work hard enough, you try hard enough, you believe hard enough, you can have those dreams you want - you could grow wings, or transform into a wolf, or be a dragon, or exist in the reality you most desire. I do not believe it is delusional therians that are most tempted by this - for myself if I wish to experience transformation I can simply stop my medicine, I do not need a special leader to teach me - but therians who are desperate, and especially those who are isolated. These places promise community and promise that salvation that some people will join these communities out of desperation. Admittedly this section does focus more on the cults surrounding learning to transform rather than the various cults built around the cosmic war thing regarding shifters as the former is the thing you have discussed more in regards to your concern regarding various delusional groups (though in a certain irony beliefs from cults are actually not considered delusion).
This brings us to the third point which sums up the other two as part of it - the importance of community. I also think it is important, going back to your original concern regarding cults and abuse, to ask how can we build resiliency within the community from abuse and cults who may wish to take advantage of us. Being a zoanthrope, having an identity heavily connected to delusion (or what people see as delusion), is an extremely isolating experience. We are often shunned from therian communities, sometimes declared evil or abusers because we simply exist incorrectly for others. Where we are allowed we must either hide much of ourselves or constantly reassure them that we are delusional but they are not. We are a social species, and we use programs like tumblr and discord because we want to find others, we want to connect with others, we want to be seen and heard, and we want to be accepted.
It is easy to think that the best solution is to make it so we are not around others with similar experience, to constantly remind us our experiences are delusion and not real. Delusions though do not work that way, insisting repeatedly our experiences are not real will often only further enforce that delusion and further isolate us. It is this isolation more than anything that opens people to getting sucked into cults. And ironically, the trend that we should not be accepted, would only reinforce those who get pulled into cults as they would see that in this small area they are accepted, but everywhere outside says they are not and never will be, a very common narrative in cults to isolate their members. We are social species and we desire acceptance and community, driving us away from public spaces and open communities will only lead to forming of closed communities we can exist in.
If we wish to build resiliency against abuse and against cults acceptance and understanding is the best way forward. We need to have a space within our community, to be able to be open and honest about our experiences without fear of reprisal. Knowing there is a place for us, and for both delusional and non-delusional therians, knowing there is a place for them, reduced more than anything that feeling of isolation. There are only a handful of CLCZ here, but having space to talk about my experiences candidly and knowing at least from those in my community has been incredibly liberating after spending so long in near complete isolation.
Isolating us and driving us out of the community will not heal the damage of bad actors in the past, nor will it fix what was done to your friend. But it will harm us, it will harm other therians who feel they must hide things to be acceptable, it will perpetuate conditions which increase the likelihood for abuse, like that your friend went through.
Having an open and accepting community is the best thing we can do to reduce risks of abuse, and intervene when it starts. How exactly that community will look in the end, and how exactly we get there is still uncertain to me, but I hope someday, together, we can build a community where we can all exist and be accepted.
