Whilst it may or may not be acceptable for somebody to be sacked for disregarding company policy, surely the two most reprehensible things are firstly that he wasn't respected for putting safety first, and secondly that he was apparently not given the chance to explain himself.
Surely, at the very least he should have been hauled in front of the chief pilot (even if he was THEN sacked).
I'm sure that there's far more to the story than we can read here, but if the story in the link is close to being correct, I'm firmly with N380UA. I hope that the fellow rapidly finds new employment with a more conscientious airline.
G