From the AFL rules:-Question here ..... if you bump your opponent fairly ... with no high contact .... but you say break a rib / puncture a lung / stuff their ac joint up ..... is that suspendable?
Or is a bump only deemed OK ... if ..... you don't hurt/injury your opponent?
"18.7.1 Spirit and Intention. Players shall be protected from unreasonable conduct from an opposition Player which is likely to cause injury".
So if the bump is a fair hip and shoulder then the contact still needs to avoid likely hood of injury - coming in at high pace at a player not in a position to brace would still result in a suspension, but two players bumping each other and one busts a rib then play on.
Houston case was probably charging anyway:-
"Charge or Charging: the act of a Player colliding with an opposition Player where the amount of physical force used is unreasonable or unnecessary in the circumstances, irrespective of whether the Player is or is not in possession of the football or whether the Player is within five metres of the football."
Charging is a free kick under rule "18.3.2 Free Kicks - Prohibited Contact"
If the ball had been kicked to Rankine rather than stupidly fisted by Keane then no-one would dispute 5 weeks here - we accept that in a marking contest the player marking the ball will be vulnerable to front on contact so have rules against that. Rankine should expect the same protection from a ball fisted 20 meters in the air as a ball kicked 20 meters.