It sounds like you think that somehow MN should have only considered the views of the appropriate left wing women.
I think the people who wanted the split were wrong, and often had an agenda, but they posted here as well. They were site users for the most part, some still post here. There is no mechanism for HQ to get everyone to "agree." Their status as users wasn't somehow less than others.
I also think it's a wild stretch to say that it's had a significant impact, almost universally the forum continues on as it had before with people posting on every topic here. Feminism chat has never taken off.
And if some people who wanted to talk about feminism in an environment that is supportive of gender ideology, you know what? That is ok. They might be wrong, in my opinion, but had those people wanted to be able to discuss issues without getting drawn into gender debates, it's really not up to MN HQ to quash that for ideological reasons, which seems to be what you are saying. The same attitudes to allowing user discussions that allowed FWR to be the only place, for a long time, where people could be critical of GI, also logically allows those who are supporters to have discussions of their own.
If some posters left over this - and actually I think almost everyone who posted before the split continued to do so after - then that's their choice. There was zero prompting or necessity for them to do so.
Really, this thread seems mainly like another of your regular attempts to decide who can speak and about what, and another dig at women on FWR whose views you don't think are pure enough for feminism.