You are - and I would be very surprised if Anning is charged. He is lucky somebody held him back though, because if he had continued to respond, he would have likely crossed the threshold Australia allows for self defence. Fortunately he had a friend there who held him back (which is what a mate does in these circumstances in the Australian conception).
The situation is more complicated for the other men who restrained the boy - I can see a couple of them being in trouble because they got involved after the boy was effectively restrained.
The boy should also be charged, although he would likely get off with a police caution if he’s never done anything like this before (and personally I think that would be reasonable).
That kid could have had a knife or a gun. That is what made this so outrageous. If that were the case the Senator could be dead.
This kid was also selfie taking his assault.
The kid is the wrongdoer here, not the man he assaulted.