I'm fairly confident that consent is an adequate defense against the charge of rape.

I completely agree that consent can be revoked or modified and that nobody should be passed around like a joint against their will. That's not what the article is describing though, at least not in my reading. The young woman who went to the party did consent, the whole way through, and didn't revoke or modify her consent until she decided to leave, and when she did, she left, presumably unimpeded. Furthermore, neither the woman in question nor the author of the article called this rape, so for you to imply otherwise seems a bit inappropriate.