There is no written law that says you have to kill the ogres immediately, or at any specific time for that matter. Just because people complete the normal mode that way doesn't mean hard mode must be done the same way. The Knights still spawn and can potentially still eat the orb. Yes pushing aetheon was a cheese especially since you weren't actually beating him. Same with Templar. You are still using all of the games intended mechanics with this strat. Timing is everything on the oryx fight. Even in normal.