If someone fires a gunshot in a crowded room and it hit's no one, would that be dangerous?
If Nani hadn't have seen it coming and hopped out of the way he could well have been missing for the rest of the season. The only reason Kompany got the ball was because of Nani's instincts for self preservation.
Those sorts of tackles have no place in the game, no coach would advocate them and no player should indulge in them.