The instance stance is that we don't allow people to undermine other folks identities. Transmeds think they're doing the "right thing" for trans folk because they think that they're protecting the "real" trans folk. People who want to undermine non binary identities, people who want to undermine therian identities etc, people who want to undermine neopronoun users, will always have a reason for it, often based around acceptability in the eyes of broader cishet society.

Just because you think there is a good reason to undermine those specific identities doesn't make it ok. You and I, and anyone else is not the arbiter of anyones identities except their own, and the moment you feel that you do get to have an opinion on the validity of someone elses identity, is the moment you have put yourself above them.

There are absolutely trolls who will misuse this kind of acceptance. But even that doesn't make it ok for you or I to install ourselves as arbitrators of other folks identity. The answer to the trolls doesn't change just because they're trolling by bad faith use of identity. The answer still remains that you remove them when they're trolling becomes apparent. But on this instance, that removal is done in a way that doesn't empower folk looking for excuses to invalidate others.