"At the time," JB had already been mouthing off that ENTIRE YEAR, and had garnered a significant amount of coverage from the sports media every time he said something controversial. He was being made fun of the in sports media, seemingly every other press conference.
So if he'd thrown a tantrum at the end, and bad mouthed SU? That would have sucked, it would have garnered some minor coverage with the sports media at large making fun of him some more, and then it would have been over. Band aid ripped off.