I don't know what's worse. The tackle or the fact that neither the referee or his assistant picked this up and they were both about 5 meters away from it. And then, as always there's the inconsistency of TMO's...
The law book and the spirit of the game goes hand in hand in my opinion. If you knowingly transgress the laws of the game to get an advantage or try to injure someone you are doing so against the spirit of the game. »
Whenever you are tackled without the ball and not expecting the hit you are much more likely to pick up an injury as you will not be braced for the impact. No one should ever expect a knee to the head while lying on the ground thus the risk of injury is much higher. That's very dangerous in my book.
Don't forget the one drama queen who comes on and declares that his love of rugby is influenced by people on a blog discussing an act of foul play and how it can and can not be dangerous. Snowflake much?