stand his ground. He was gambling that Fouss would make another power move to the basket. He won the gamble. Fouss hit him straight in the chest pretty hard, and he wasn't standing his ground, so he flew backward.
To me, a flop is faking a hard hit to exaggerate and deceive the refs. I didn't see it on that play. And I'll tell you what, I have no desire to have Fouss hit me in the chest like he hit that player. Any of us would probably go flying as well.