Hello! One question. Is it a thing? Calling fans that police canon "curative fandom"? It's just that I feel it can be confused with "curate your own fandom experience" that I've seen in tags and as necessary discourse, meaning that you shouldn't harass others for liking/shipping something you don't like/agree with, you just unfollow them, which I find to be a positive discourse, as opposed to trying to "curate"/police whether something is canon/valid in fandom or not.
Curative fandom as I've usually seen it used by others just refers to people who are primarily invested in celebrating a piece of media's canon, which isn't something inherently negative.
Curative fans are collectors who like to learn as much as possible about all aspects of established canon. And some fans may be both, or may be more of one depending on the fandom (I myself am far more of a curative fan when it comes to Star Wars, at least the old canon, than I am in any other fandom). Curative fandom and creative fandom aren't opposing groups, and curative fan activities can inspire creative fandom activities.
A great example of this is fans learning as much as they can glean from canon about a fictional language and then filling in the blanks to create a cohesive, usable language in the real world. Another example is fans doing artistic reproductions of maps, scenes, clothing, weapons, etc. from the source material that are as faithful as possible to canon. A lot of meta falls into this areas as well, IMO, relying heavily on knowledge of canon while also expanding beyond it.
The problem I have with curative fans in some fandoms is when they move from celebrating canon to feeling the strange need to "defend" it, policing others' ways of engaging with and enjoying media. You see this dovetail a lot with other negative aspects of fandom, such as ship wars and gatekeeping. For those extreme types of curative fans, anything that deviates from canon is perceived as either inherently wrong or an outright attack on the thing they love, when really it's just a different way of engaging with that thing.
As for the possibility of this term being confused with encouragements to curate your own fandom experience, I think there is enough context to not confuse the two, especially when the latter is stated so many different ways. Manage, you're in charge of/responsible for, etc. That being said, I'm not about to tell the whole of fandom how to refer to anything, or what any word should mean. Just ask policers of the word drabble how well that works. 😂