Marco gets up as well when Jean does, watching Jean look a little huffy about the puppy getting cuddled instead of him. Really, Jean? He's just a puppy.

Mikasa's admonishment does have Marco raising a finger to scratch under his nose, a nervous habit.

"Ah, I'm sorry, Mikasa. The way Jean has been acting, I didn't really think he'd be a threat. But you're right." A werewolf had been dangerous enough to scar Jean, after all, so Marco should have been thinking of it.