alan joyce pie
We were on the same flight back from Perth as him, got one of the good gates on arrival, and the talk on the flight was it was that the guy was from a christian group and the attack was related to his and the companies support for marriage equality, of course he could have been protesting the direct flights to London.
However this was just "crew musings", or maybe they heard discussions, I guess in time the offender's motivations will be revealed. After all if he doesn't he's wasted his action. It would be like a group of protesters arriving out the front of the Qantas offices holding up blank sheets of cardboard while saying nothing. Mind you that would make the basis of a great python sketch.