If I'm remembering correctly this was either the genesis or major exodus to terfy alternatives like Ovarit. Like many webforums places like TwoX or lesbian subreddits eventually found trannyjannies on staff and they did their long march like they always do. Eventually prohibitions on outright hate-speech turned into accusations of prohibition being transphobic. I think there was even a poll or two where it was made abundantly clear the vast majority of users did not want trannies. Funny enough the TJ's used that as evidence of rampant transphobia that meant they had reason to unilaterally let their ilk in.
Kind of like a dam failure, a tiny trickle turns into a flood. Anyone critiquing the decision or voicing their opposition were banned with a quickness. If you only look at numbers and not content, it's easy to miss them in the incoming flood of terminally online AGPs. Once it was clear they had a pattern that worked the TJ's began moving on other subreddits. Strangely enough, porn subreddits proved hilariously resilient to the same tactics.