I saw a competent, independent, amused and amusing young woman, who, as you say, invited a man who began to interest her (vaguely!) for a little fun.

It's one of my favorite scenes in the movie. It's one of many people's favorite scenes. I think they see the same things in her that you do. I don't know why David Thomson couldn't see them. If you're going to make the argument that she's a fantasy, then it must be acknowledged that the appeal is not only to—or from—the male point of view.