The people I tend to agree with are just as prone to group think as conservative-leaning people. Hate grows in the absence of disagreement, and it doesn't stop at the echo chamber's walls.
So what do you actually want from a community then ?
It seems like you don't want certain people in it, but at the same time you do want them in it. I'm not sure if I'm understanding it correctly.
I'm assuming he doesn't want a community with only people he doesn't like nor a community with only people he likes. So he wouldn't move to a service where all the people he dislikes moved.