https://news.ycombinator.com/item?id=30899950
I'm not up on my billionaire gossip so I have no idea if Dorsey and Musk are friend or foe but I can certainly see where someone would regret building something powerful and then letting others (especially those with different views) control it.
I could be very wrong but the impression I got from watching several interviews with Jack (like his appearance on Joe Rogan) he seemed to have been very very torn by the desire to be a more free speech platform while still being in a constant battle with his Activist CA based employee's
I think this battle is why he left.
He totally could have known, since the paperwork was filed a few weeks ago. Did he look into the paperwork? Maybe? - if I found a major biz, I'd keep my EDGAR alerts turned on.