Under cutting?

NCAA: "Every player shall be entitled to a spot on the playing court, provided that such player gets there first without illegally contacting an opponent" (4-17.3).

NFHS: "Every player is entitled to a spot on the playing court, provided the *player gets there first without illegally contacting an opponent" (4-37-3).

NBA: "In all guarding situations, a player is entitled to any spot on the court he desires, provided he legally gets to that spot first and without contact with an opponent" (NBA Comments on the Rules, II-A-2, page 57)

Let's not pretend the rule sets are so different. The only difference is that the NCAA has a case play and the NFHS does not. I would call the OP a foul under both rule sets, it's pretty clear that a defender laying on the floor is not in LGP.