Mastodon is more than the Gmbh. The fediverse is bigger than Mastodon. There are already popular community server and client forks of Mastodon. The 501c3 board in the US isn't a bad thing. ActivityPub is a w3c governed spec, and there isn't nearly the same level of scrutiny around w3c's board, because it hasn't been an issue. All that to say, I'm not at all concerned about this.
