Look at the responses to this tweet:I think what I'm talking about is more (or at least different) than a big public "sorry". What I'm looking for, personally at least, I can't speak for anyone else, is an acknowledgment of the harm caused. Just... take responsibility for it. That's all. "Look, I said this thing, I did this thing, and it was wrong. I have heard the pain that my actions have caused, and I am sorry for it." That's really all it takes. Any other fol-de-rol about the importance of taking survivors at face value and supporting them, of rooting out those within the industry (if not hobby) who perpetrate violence against others, etc.; that stuff'd be nice, and maybe there are some who would insist on all of that as well, but I think the vast majority of the people who are looking for more would be more than satisfied with him acknowledging his public statements in defense of Zak (and particularly his public-adjacent statements denigrating those who were trying to warn everyone else about Zak).
A cursory read of the responses to his last tweet makes this, I think, plainly obvious. Dozens of comments in and I've seen one ad hominem insult, a few references to more egregious events I haven't been able to verify, and a whole bunch of people simply saying that this statement wasn't enough, and they were expecting more from Mearls, personally.
Hell, if all he did was come out and say "Look, I'd love to say more, personally, about all this, but legal has my hands tied" I think that would satisfy the bulk of them.
People don't want an apology. They want him investigated. They want him fired. They're not going to be satisfied with him making a statement of contrition. He's better off keeping his head down and out of the public eye rather than returning and reigniting their ire.