To your leading question (remainder of your post spoilered to focus on this),
this article makes the case that moderation
was Twitter's primary product and, as such, it was
an essential part of their business. It wasn't that Twitter owed moderation to everybody else so much as they owed it to
themselves.
We've already seen what happens when you gut the moderation team and relax rules about what can be posted: it's an unmitigated mess that a lot of people and companies want absolutely nothing to do with. (Note how this also verifies the thesis of the article).
Elon Musk's current hell is very much of his own making, and he has no one to blame but himself for the loss of advertising customers and high profile account holders. And without those, he has no route to financial viability without taking away from his other business ventures.