They’d want to check him out, but they would go pretty easy on the guy. Unlike the Deans (holy shit is BT Dean going to give BA Dean hell when he gets back to the Lounge and he’s the tallest Dean in there– how many times did BA Dean keep him from drinking! Karma, bitch), the Sams are pretty easy going.
They’ll probably have some races, see if Oscar can keep up with them, in general keep their Deans fretting over the daredevil stunts they come up with, and have a good time all together.
BT Sam will have the most balanced diet growing up (even with Dean’s addiction to bacon cheeseburgers), making him the healthiest of them, especially in the beginning of the AUs, when Dean first rediscovers Sam.
Sam’s used to his clothing. He might be a little jealous over how BA Sam’s fits better, but he doesn’t mind his own clothes. It’s definitely good to have a little extra padding on a hunt.