My two cents, (and believe me, I think its worth half that), from the Federation POV and the way it was taught to me was that this was not a "hold" per se as the wording in the rule book clearly states that the body is incapable of grasping, hooking, locking, clamping, or encircling the opponent. The rule reads very briefly, IMHO, that when anyone on the offense except the runner uses his hands, arms, or legs to lock, clamp, grasp, encircle or hold an opponent in an effort to restrain them it is holding. As we are not using the hands arms or legs, can we call it holding??? Sure. The spirit of the rule is there as they are restraining the opponent, but I will talk to the player first. IF after the second time, I call them over and state that what they are doing is a personal foul or unsporting conduct (No one shall hinder a player by an unfair act), and this will normally alleviate that action from occurring again. Actually, I don't think I have thrown a flag on that at Varsity level. Again, just my way and everyone is different. Put 100 folks in the room and get probably over 85 different answers.
Cheers!