I guess it’s cause I don’t know much about kids, but why would you worry about breaking a kid of sleeping with a stuffed animal? What kind of damage do you think it’s going to do him?
Yeah, it’s a little unusual for a boy of his age (not at all unusual for a girl that age, though–when I was in college, a lot of the women in my dorm still slept with stuffies), but it’s harmless. If he takes them with him to boot camp, his drill sargent will mock him in front of his fellow recruits and shame him into giving them up, but that’s really the worst harm it could do him.
It’s not even necessarily a sign of immaturity. I mean, a lot of adults don’t really sleep well when their routines are disrupted and need something familiar to comfort them. It doesn’t strike me as all that odd for a child to want that sort of continuity when his routine gets disrupted every week or two.