[He tries very hard to make it look like it does! ... Which means, yes, he's apparently always putting a little focus toward making sure his magic morphs the neckhole and keeps it snug.
He's a dork.

... As for Kokichi's quick escalation, Chipp's dropping that helmet back on for the delivery of -]

Hun, I kill the folks who do that.

I just like makin' kids laugh, me! They still got their whole childhoods to go through - they deserve to laugh as much as they can.