That's not what it actually says. It says it's red "unless the force used was negligible." You could have a player whose arm is outstretched and an opponent runs into it. So the player whose arm makes contact with the opponent's face has exerted no force whatsoever, yet you still have fairly significant contact. It's not the amount of contact, it's the amount of force used by the player in making the contact.
Again, the law doesn't talk about 'something' (or the overall challenge itself) being insignificant, it talks about the force used being negligible. For me you could have an incident where even though the amount of force used is negligible, the actions leading to the contact occurring could still be considered reckless - or constitute an act of unsporting behaviour.
I don't think that was the case here, just that theoretically it could be.