I suspect that Sutter was merely trying to motivate a young player via the media there.
I think he's more or less "challenging" Muzzin to step it up and earn more Ice time on the left side. Telling him that he's got the opportunity. He's being shielded so far, but he hasn't looked out of place yet.
I wonder if he's capable of doing a "Voinov" ... show that he's ready and capable for the big time, to force DL to make a decision. He'll have a tough time bumping any of the 3 "lefties" out of the lineup.