I agree that sacking the guy was extreme. Perhaps suspension for a few weeks would be more appropriate.
But c'mon, you people can't defend his inappropriate actions (even if he was inebriated)! As a captain, he is "presumed" able to demonstrate appropriate judgement. Instead, his actions were directed, juvenile and inappropriate. That is unequivocal.
Now, if he were a high-powered politician, you can be sure that his actions would have been vilified in the press and he would have been pressured to resign for demonstrating poor judgement and acting inappropriately - in a way "not worthy of his position". You know that would be the case - whether you agree with it or not.
I agree that sacking him is too harsh - suspension would have still sent out the same message. He is probably a great pilot/person when he is sober - firing him is too extreme.
Cheers