That's fine. This is a case of "I'll know it when I see it"

If I saw you swinging the grasp arm so that it made forceful forearm contact front-on to the kicker's kneecap, or if you shoulder-charged into the kneecap and I thought wrapping was an afterthought, I would warn you that your technique is dangerous to the tackled player. If you keep doing it, you'll give me no choice but the think you are deliberately trying in injure the player, which is an infringement liable to severe sanctions.

Trying to purposefully injure an opponent is definitely not within the spirit of the game.