I actually think the TMO (? Leckie) who was standing about 10m away staring straight at it and who did nothing was the most puzzling thing, in a way. I mean it was pretty obvious contact with the boot to the head / head area in real time right in front of him. Foul play / potential foul play seems to be the most likely reason for an AR to want to get their head on TV. I suspect that the fact that Palmer jumped straight up and got back into it was the main reason it was overlooked.
Don't try to rationalise the citing process - it would be easier to debate gay marriage with Tony Abbott.
Anyway, no harm done, and in years past we would have all gone "Whoaaahhhh, Palmer got worked over!!" with a tear of joy in our eyes, and secretly liked that we thought our Wallaby captain, and our THP, were 'ard!!