Other than at scheduled air shows, where these maneuvers are well thought out and detailed beforehand, I have never understood the propensity of some pilots wanting to make low passes over the airfield/runway, just for the heck of it.
Poor judgement, it would seem to me.
Imagine if a flock of birds just happened to cross the runway at about the same altitude as when the low fly-past was accomplished...CX sure would look foolish with an expensive new 777 all rolled up just off the end of the runway.
Yes, the same thing could happen at takeoff, but that is entirely different, in my view.
The concerned Commander certainly left his brain out to lunch with this stunt...and that is precisely what it was, a stunt.
Deserve to be sacked?
Darn right, in spades.