Jacinda Adern Headscarf ., page-89

You can use reasonable force in self defence, there was noting to suggest Anning was in any further danger after having an egg cracked on his head. The action of Anning punching and restrain used on the offender was disproportionate, Anning and his minders may well face charged them selves.

There are examples of people assaulting and intruder that has resulted in assault charges

I'm not saying that this guy should get away with what he did, it was a prank and there was no danger of Anning suffering an injury so it's a non violent attack.

Anning throwing punches could have resulted in injury and looks like that was the intent, that is classed as a violent attack