Well, I don't think Reborn is actually going to win win. If he does win I'm 99% (hell, let's make it an even 100%, there's really no doubt in my mind) that he's going to offer the prize to Uni because come on. "Sorry about that, I know you kind of had your heart set on not having your young life cut tragically short due to the curse and all, but I was really looking forward to turning back into my badass adult self, so... them's the breaks." He doesn't even seem to mind being a baby all that much, so it's the gentlemanly thing to do, really.

And of course as you noted, there is always the possibility that Checkers can't be trusted, which would not really come as a shock. XD