You mean that mute where you click your opponent's avatar?
I think it works, but those symbols might be a bit wonky. It shows red X when your opponent isn't muted and other way around. But then again, I didn't pay that much attention to that, so I might also be wrong in here. My opponents didn't emote me after I had clicked their avatars once (and saw the "voice on" symbol). Might also be just lucky coincidence.