Hot take: Software is morally neutral. Just because some bad people may be using Pleroma for their instance, doesn't mean that Pleroma, their devs, or others using Pleroma for their instance are bad. I'm sure some bad folks also use Mastodon.
I know the Pleroma devs, they are good people and definitely aren't nazis, and are actually hurt by the idea that people think they are. We should not be discriminating based on platform unless we know a *platform* is evil, not the ones using it. Bad people can use any platform they install.
So can we all stop blocking people just because they are on a Pleroma instance? Or not relaying or federating with an instance just because they are Pleroma? We actually do need the software diversity to inspire new ideas.