Who knows if they'd actually sell it for billions or not, but it's a problem that solves itself. If it's ever worth billions that could only mean that it's attracted the eternal September away from Twitter/Reddit/etc. in which case it won't be worth using anymore. Anyone discerning will have moved on to the next Bluesky that's too small to be of interest to billionaires.
It seems this claim would be more accurate to Mastadon as that is open source right?
Blusky is proprietary and could still be acquired by anyone…
bluesky and atproto are open source. basically every part of the stack is open source and self-hostable. The only part that isn't is some of the backend appview stuff for bluesky's implementation however they maintain a reference implementation that can be self hosted as well.
This is the theory, certainly. In practice, I do wonder if the centre of gravity would shift fast enough, were it bought by an insane billionaire, but yeah, it is at least theoretically closer to immune to this than Twitter was.