I seriously wonder what possessed him to tweet that, especially given that he already knew he was under scrutiny.
It strikes me as the tech equivalent of joking about bombs in the security line--yes, technically free speech, but pretty guaranteed to have some unfortunate results.
He was seeking attention
As he should be.
Technically free speech but not really means censored speech. Pushing the boundaries of freedom is a virtue in and of itself, for if we do not push on them, they will slowly strangle us.