"radical child liberation implies right to leave. And right to leave annihilates the plot of the novel completely. Not by the time Humbert is having sex with her; not even by the time Humbert becomes her guardian; even by the time she is still under a living Charlotte's custody, the right to leave destroys all the premizes."

Which "right"?
After Humbert violated her, she had the practical ability to tell police directly or through her school teachers that she was abused, and get put to orphanage/foster care. I suspect that she still had the right to do so after being thrown out by Clare Quilty.

She did not choose that. She chose independence of working in scullery, and then Richard Schiller, who was not as bad as the other bad options.

A "right to leave" is not all that matters. What makes the "right" usable and relevant is practical options where to go TO. And these are not yes-no question, because how acceptable these are depends on individual judgement of exactly how bad staying is.

Also: Dolores always knew she had the opportunity and "right" to leave Humbert and go to foster care. Yet Humbert impressed her with how bad foster care was - and called her naive for believing him.

If police comes across an abused child - or an adult battered wife - who acknowledges that she knows she has the "right" to leave, and tells she does not want to leave, and suspect that she is mistaken, or deliberately misled by her abuser, as to how bad the alternatives are, how much should they be allowed to inform her?