I agree that a leg breaking tackle is more dangerous,but it's about what it deems is acceptable or not.
If you call a black person a certain word on the field you are going to get lengthy ban-you have not broken their leg but it's not acceptable to say that,just as it's not acceptable to physically bite someone as he did,spitting is also a no-no.
As a humble local footballer in my day a hard tackle was accepted and once i felt my leg bend-close to breaking!,but if some one spat at someone it would start a fight to be sure-it's disgusting.
Do think it's a bit inherent in players from south America to some extent