I agree. Players HAVE done that forever.

It got old. No one likes it. And I say that acknowledging that there's a difference between exaggerating actual contact that occurs and faking contact that didn't. But no one likes the over-exaggeration of a player looking like they've just been hit by a projectile in a Tarantino film that has launched them across the room.

So they've made rules against flopping. This is the first year they've had them in play. You can read about it here:https://www.ncaa.com/news/basketball-men/article/2019-11-05/mens-college-basketball-rule-changes-know-about-season

"On a block or charge, if the player’s head goes back before the body does then the player could be flopping. Can there be a foul and a flop? Collins said yes. That’s when the offensive player makes contact with the defender and hits him enough that the defender steps back and embellishes the contact. That can be an offensive foul and a flop."

It's really hard to watch a replay of that particular play and NOT see that Seljaas head flew back before his body. Was it a foul? Maybe. Was it a flop? Yeah. It was a flop by the definition the NCAA has instructed refs to look for.