Well, here is what he did and why. The player was kinda short. So on long shots where he could not reach the cue ball, instead of using a bridge that he was not comfortable using, he would simply turn his stick around, lay the butt end on the table only a few inches away from the cue ball and push his stick into the cue ball. Using the butt end would not cause the cue ball to jump in the air as it would if using the cue tip. Now I agree that you are not going to get and accuracy or English if needed, but I thought it was kinda cleaver.
If stated that it is a foul, I would need proof from the APA rule book in which I cant find any.
You can't hit the cueball with the stick on the table that way. You can't hit it with the butt end either. APA or not APA, those are standard pool rules. It's like looking for a rule that states you should not hit your friends in the head with a hammer in the "how to be a good friend" manual. Some things are just general rules that apply to everything. APA plays around with some rules of games, but not the overall rules that govern what is a legal shot.