Add a "Mute" Trait

[RelentlessGarbage]

The mime is an exception to this, but part of that is they're dressed like a mime: Another player can see that and immediately understand that they won't speak back.

If this was a trait, you wouldn't as easily be able to parse that.

There's also the aspect of antisocial minimaxing for turbo murder

That's fair; adding it as a trait might cause confusion, since you'd have to examine the person to tell that they were mute. As for antisocial minmaxing, that's also valid - making the trait give no points might solve that so you'd take it purely for the aesthetic. (The inability to speak does confer some problems for muderhobos, though, so I think it being +2 is reasonable, but for the sake of discouraging trait abuse it can be point-neutral.)