I think that's fair though. If you create a community for conservatives to speak to conservatives then that is who you want there. If you're in a community about skateboarding, you don't want to be inundated with people constantly saying that skateboarding is dumb.
(To give some context, I do happen to think conservatism is dumb, but I'm also able to see their point of view and why they would want private communities online. I have no opinions on skateboarding)