Being that the Masters was USBC certified, did Belmo(and other no thumb bowlers)have to make sure all his equipment fell within the new no thumb release, thumb hole/weight hole guidelines. I didn't get a good look to see if any of his balls had a thumb hole and a weight hole. I imagine they didn't, but that would be a bigger controversy than towel-gate.
http://usbcongress.http.internapcdn.net/usbcongress/bowl/masters/2015/MastersRules.pdf