He should STFU, yes.

However, if you draw a distinction between premeditated murder in the first degree, and what Chauvin was convicted for—second degree murder, non-premeditated, but an assault where death was a very possible outcome—then there's an argument that Chauvin didn't "mean" to kill Floyd in the sense that he thought to himself, "I am going to deliberately kill this man today." At least, that wasn't legally provable, I guess.

So if that's the line that Favre meant, then there's that.

Realistically, though, Favre likely didn't have fine legal distinctions in mind. More probably he struggles to understand that regardless of what Chauvin did or did not premeditate, he chose to try to demonstrate such power and control over another human being that he didn't care whether that person lived or died. Which in some ways is worse and scarier, because that's the behavior of a psychopath.

Anyway, the moral is, fuck Favre. Just trying to think through what he said.