he evidently "dared" with Margaux, right?

Yes, but knowing that what he did was illegal, a key part of his daring was the confidence that she wouldn't tell on him.

Dara is gorgeous, strong, assertive and confident. Why would he be frightened of her? Who's frightened of girls and makes them stop rough-housing? Someone who's worried that if he follows his desires he might end up doing something for which he'll get in big trouble. If it wasn't illegal, he might just say she liked it at the time but later changed her mind.

Dara ... would definitely keep the hands of anyone they didn't want on them off of them

Perhaps, but he could first find out whether she wanted his hands on her or not.

Maybe emotionally strong partners were just not to his taste -- but that wouldn't make him afraid of her. And it wasn't total fear -- he had the strength to set limits with her.

It's not an open and shut case, I admit. But I think it's strongly suggestive.

In a youth liberated society, the great majority of kids would be like Dara

We could help our kids become strong and confident without changing a single law, and plenty of kids would still be messed up if we changed all of them.

Your "youth liberated society" sounds like a utopian fantasy. There will always be bad parents, and kids who don't have the strength to even perceive that there is a problem.

There are issues you and I could even work on together that would improve the emotional resilience of kids a little, but expecting big changes is unrealistic.