Because.
His brand of football was turning people away from the club.
He openly flaunted his condemnation of the boards actions in trying to reduce costs. Not least by his ridiculous and, for my mind, childish decision to name a reduced substitute list rather than give youth a chance and running to the media with complaints about finances.
Furthermore. It seemed that Gus wasn't accepting the reality that cuts would have to be made this season so, in actual fact, a person with higher morals might have walked rather than be pushed.
Finally.
Because what we were witnessing on the park was woeful and the capitulation at Hampden was one of immense proportions.
I don't understand how anyone can seriously believe that Gus was the messiah and would steer us clear of relegation yet again given that he would have definitely lost Dorman and Mehmet, propably Innes too given those financial limitations.
Maybe he'd have kept Johnston, O'Donnell and Ross!
If you keep jumping on a trapdoor, chances are, it will eventually open.