Restricted spaces are necessarily smaller than non-restricted. Less content. Less interaction. Less everything. If hateful content is really rampant, then that can be a valid tradeoff, but separate systems are never equal, and it is always the minority/marginalized system that suffers. You’ve described exactly why: “I would find a new instance and continue to be receptive to LBGT+ discussions that come up on Lemmy.”
As I look elsewhere in this thread, the comments I see people reference as “against Beehaw goals” are just people being rude assholes, not misogynist, racist, or homo-/trans-phobic. Creating a space where everyone is polite and universally friendly seems a very different objective than creating a space where marginalized people feel safe. If that - universal friendship - is the real goal, then Beehaw very definitely needs to close off interactions with non-vetted, pseudonymous users, and accept that it will look like a virtual ghost town. In that case, it doesn’t matter whether it stays with defederated-by-default lemmy or moves to some other forum platform.
The middle ground, where you accept that some people are just rude, but still provide a forum where marginalized people feel they can share their experiences without threats or repercussions, needs strong, active, focussed moderation. Have to be able to block users and communities from other instances, delete posts/comments that originate from other instances, and do local moderation of communities hosted on other instances. Have to have enough moderators to respond quickly to user reports, and probably an automod-like system to catch serious issues before users do. It sounds like that is not within the current capabilities of lemmy. So, I can see why the admins think that the lemmy framework is incompatible with their objectives. Probably, a lot of the people who joined post-Reddit are incompatible and uninterested in those objectives.
I can see where the lemmy framework worked when no one used it, and I can see why it would immediately fail in the face of hundreds of thousands of new users. If millions are coming, it will only get worse. No doubt, the admins are aware that they’ll lose 80, maybe 90% of their userbase if they leave Lemmy, but it’s not so long ago that their userbase was only 10-20% of what it is today.
If I lose this little window into cultures I would not otherwise see, I will be a lesser person for it, but I can accept that it was not meant for me in the first place.