To me, it really comes down to who attacked first. The age/size difference is irrelevant if it’s self defense.
Watch the video.
He went nuts and slugged a little girl after first shoving her down.
https://www.liveleak.com/view?t=spiRI_1547359280
No excuse at all as far as what’s on the video.
Looked like one of those girls pushed him from behind.
I'm thinking the same thing. It looks to me as if she came right at him with clenched fists, ready to slug him.
If men are going to be chivalrous and refrain from hitting women, it's incumbent on women never to use the men's chivalry against them.