It wasn't a command, just a matter-of-fact statement. Jesse hadn't been paying attention to the kid's dietary habits, since it didn't seem like his business, but he's not just going to stand by and watch Stan and the baby starve now that he knows they're eating worse than Oliver Twist up in here. Jesse's the adult, so it's his responsibility to fix it.

"You guys have a good nap." Both the baby and Stan, he assumes - because nodding off is what stoners do.