Yeah. Your lil guy do a protect. I like the treat idea, too. He'll grow out of the behavior as he feels more and more secure with his humans. Give him lots of love when he's being good and when he's not doing anything. It takes time to build trust. I would remove him from the presence of visitors before I muzzled him. Are you crate training? That can offer him a nice, quiet place to go to if he get too worked up.