> It is pretty hypocritical though for Mr. Free Speech to fire people who have concerns rather than address those concerns in a civil dialogue
No, not really, since this has very little to do with free speech. Free speech does not mean that you can communicate with your superiors, or in fact any other person you're in some relationship with (spouse, family member, etc.), in arbitrary ways with no consequences.
who knows what it means for Musk. he said (paraphrasing) that whatever is legal should be allowed on Twitter. this doesn't really mean anything with regards to his speech at work views.
if we want to somehow generalize the ethos of whatever is legal should be allowed (so basically he thinks Twitter is too strict) then we might conclude that he favors more "open dialogue" and this does feel contrary to firing employees for criticism. (though I haven't seen the letter, it's possible the authors/signers explicitly said something that simply make it clear that they won't continue to work in this or that way, and the company decided that okay, the company won't change so they have to go anyway - see the Gebru ultimatum)
Twitter is specifically a medium providing its users (the public) the ability to communicate with each other. It's literally their business. Musk's view that as a public communication medium, Twitter should be permissive, has nothing to do with internal processes at any of Musk's companies. Hell, it has nothing to do with internal processes even at a hypothetical Twitter with a more permissive user ToS since the behavior of Twitter's employees is guided by their employment contracts and guidelines, not by Twitter's user-facing ToS. This would be true even if Musk weren't to ever become a majory shareholder of Twitter.
No, not really, since this has very little to do with free speech. Free speech does not mean that you can communicate with your superiors, or in fact any other person you're in some relationship with (spouse, family member, etc.), in arbitrary ways with no consequences.