Maybe he was a lousy employee and the boss had finally had enough. I guarantee that there is more to this than some comment.
He was fired and then told the press he was fired for making the comment
Very likely you are correct. Plus, he also would likely be a huge company disruption, potentially with violence involved, because the company is located IN Tennessee. Probably many employees are Tennessee fans that are very angry with this guy. The company probably did not want to assume the responsibility of protecting this creep from his fellow employees.
Full disclosure: I am an Auburn fan . . . even when it hurts. . . .