That is not a right to leave. To report to police is no right. It implies by its very premize that normally she must stay with him without question or recorse, and that the exception created by her sexual abuze is that, an exception.

Right to leave implies she can leave at any moment, for any reason. Without being retrieved back to the parents nor taken into foster care. She would not have had to put up with Humbert since the first moment she felt wrong about it; either by choosing to leave or by threatening to leave and demanding her conditions. Same with Quilty. In neither case implying that she would have to report them to police or go into foster care, but simply that she could go to anyone who would take her (as first Quilty then Schiller did, but without the possibility of the takers themselves being subjected to legal penalties for it, which would make shopping for takers far easier and safer.) Even before Quilty and before entering into a relationship with Humbert, upon the chance of being sent by Charlotte to a boarding school she didn't want, with a right to leave Dolores would have the chance to shop for takers who wouldn't send her there.

So still, radical youth liberation clearly leaves the novel without any of its premizes.

And still, this is why it cannot be used as a thought experiment for what would happen in a radical youth liberation society. Because its characters, all Lolita, Humbert, Charlotte and Quilty, and even Richard, choose what they choose based on a society which is not youth liberated.