When you're here (or at any school) on a free ride - free education, free housing, being fed - that is a job, and it comes first before all other non-academic obligations. I'm sure any time any player agrees to do some sort of public appearance, there is the understanding that if something relating to their job comes up, that takes precedence and the appearance will have to be rescheduled or canceled. I seriously doubt he just decided "meh, I don't feel like doing it, screw them" and backed out, like some of the Bama haters would love to believe.