I do world commissions for LGBT creators/communities, and I assure you that the discrimination is something that’s already happening, and this ban feature is something we’ve been asking for for a long time now to help combat it. These communities (at least all the ones I know of/make worlds for) would much rather have a safe ‘pseudo-public’ space for themselves without certain people, than the ability to go to any other group’s instance without fear of being banned there. Temporary ‘instance bans’ already exist in the form of in-world moderation tools - Group bans can have their own separate usage for the more obvious or repeat offenders.