I think there's another big cohort you're potentially missing: people who literally just want twitter.
as much as mastodon is twitter, the decentralization makes some things significantly different. and as much as bluesky is supporting decentralization, everyone who's joining it right now is treating it as a single platform, from what I can tell. and the people I see leaving would never have left for mastodon because of the decentralization.
i mean, fair enough that their moderation story is really, really lacking, but even among people who know it's going to be badly managed, i think you've missed that there's a significant group of people who know that, and also value a unified, twitter-like platform more than they value that platform's management.
I guess you could say that falls under "ambivalent about platform mismanagement", but I think that saying it that way completely discounts the other reasons that one might want to use it. platform management is not the only variable here.