Two set of rules apply

Seriously though, there was a similar incident in England in an Aviva semi-final last weekend, when the retaliator was sent off (as the law requires), and the ref gave the instigator a yellow card, which seems fairer than the guy who started it all getting off scot-free. But the inconsistency of it all was highlighted about 3 weeks back, when the Brumbies hooker, Stephen Moore, punched an opponent in retaliation for - you guessed it - being held down at a ruck. Ref Walsh saw it all on the big screen and, mind-bogglingly, decided to take no action against Moore, and even went back and awarded the Brumbies a penalty for an earlier infringement! Even more amazing - but perhaps not too surprising in light of the lack of action against Aussie players over the years - Moore was not even cited afterwards, in direct contradiction of the rules against retaliation and, in particular, punching.