I feel like you have verbalized a sentiment a lot of us have been feeling for a long time now, and I especially identify with this as an a-spec kinkster myself.
I'm going add something now that some people are not going to like: we wouldn't need a sfw community if we were unified in keeping minors out.
I think the majority of us realize that even if your interest in tickling is completely non-sexual, if you have a blog dedicated to tickling, you are not "normal" about tickling.
Because the reality is, the average person doesn't just sit around thinking about tickling. Whether you call it a fixation or a kink, if tickling is regularly preoccupying your thoughts, you do not share the average person's feelings toward tickling. Point blank.
This is an activity that involves touching other people's bodies. It is not okay for an adult on the Internet to be talking to an underage person about an activity that involves touching all over their body, especially in more private spaces like DMs or discord servers. Yet, new "16+" or even, appallingly, "13+" tickle discord servers open up and get advertised on Tumblr all the time. Big blogs spread these around, too.
It's weird, it's wrong, and the adults who are doing this are both taking advantage of the minor and putting them in danger. Because even if THAT adult isn't truly going to hurt them, who's to say the next adult who comes along won't? The people doing this are setting an incredibly dangerous precedent, whether they are actually a predator or not.
As long as we are divided on this issue, this community will stay divided. Personally, 95% of my art is nonsexual. I still don't tag it as sfw, because I KNOW that tag is full of minors. It also happens to be the biggest tag with the most "reach" in the tickle community on tumblr and it's exactly because of that -- it contains all of the minors and all of the adults, whereas minors tend to say out of the tags that aren't sfw.
So... if you're trying to get your work seen by the most people (and especially if your income depends on it), guess what tag you're going to use? Even if your art has bondage? Even if your art has people screaming for the tickling to stop? Even if your art clearly contains bdsm elements that would absolutely require consent in real life...? The sfw tag, of course.
I know a lot of people hate seeing this issue brought up, but I'll be honest -- every time I have thought about leaving Tumblr, it has been about this. I am also into sneezing, general bondage, and other kinks (or fixations, if you prefer) that are not inherently sexual. I cannot stress this enough: those communities DO NOT have this problem. There is NOBODY advocating for minors to be able to participate, they are unified in keeping minors out. They do not have a split community like we do, but they do have PLENTY of asexual people, just like we do.
I'm sorry if this comes as a shock, but it's not about nonsexual tickling enjoyers vs sexual tickling enjoyers. It's about people making space for minors in this community or not.