The principle that "a coach who makes a true statement never deserves a T" is incorrect. In addition to being a wisecrack, which seems to be the case here, the true statement could also be:
a. overly demonstrative, showing up the official,
b. include profane gestures,
c. personal ("you suck" gets a T even if true!),
d. prolonged, and occur after the coach was warned to keep his comments to himself.

The truth is no defense.

Are you f'ing serious. It's no coach's business, head or assistant, what I am talking to my partner(s) about. And if he has a smart comment to make about it, especially after being chirpy all game, I'll T him and not think twice about it afterwards.