You're wasting your time if you truly believe that Bluesky is not going to end up the same way.
Remember: all this shit started with PayPal, they have tons of money and can afford to buy up any place where sanity still prevails and if BlueSky is that place then that's what will happen - again.
Indeed, there are the same incentives and commercial pressures. But you don't have to believe that that it will last for ever, you can dance while the music plays, and be prepared to leave when it stops.
Choosing when to leave as a platform gradually enshitifies is tricky, but making your peace ahead of time with the idea that it is temporary is good preparation.
I understand that not signing up in the first place is a valid choice.
But I also feel that using these services, on the understanding that they don't guarantee to remain good, and so you don't guarantee to remain there at all when they succumb, is also valid.
You don't owe them that. Another one will be along in a minute. That's why we went from MySpace to LiveJournal.
"legitimacy" is not binary nor eternal, and Elon's mouthpiece is leaking it's remaining legitimacy.
I follow many people on BlueSky that I followed on twitter, and I don't feel that I have a valuable brand, that's not what I do.