It’d be interesting to see how much of Mastodon’s source code they actually end up using for this, because that would significantly cut down on their ability to embrace extend extinguish. I think there’s also rumours that Tumblr are looking into ActivityPub as well, which would also keep them in check.

IMO it’s too early to really get upset about this, and I don’t think “big company uses X” is sufficient reason to block them. But I’m not an instance admin or anything, so my thoughts are just rambling.