I think Bialek wanted Cain to remember her when she hugged him, but not for the sexual assault she claimed happened long ago (because it didn’t happen). I think it galled her that he didn’t remember her at all for the things she was probably partially truthful about - meeting her and her boyfriend at a work dinner, going to his private party later that night, etc. At that Tea Party event I think her hopes were to reestablish a connection with him knowing his star was on the rise and she could latch on in some way or the other. Failing that, since Cain didn’t remember her (why would he), she took the next opportunity which was when the other allegations broke - she would join the chorus as the star witness and cash in with her phony claims of assault. The timing was right for this theory as she was preparing for yet another bankruptcy and her live-in boyfriend was jobless and going broke also.
Notice she is smiling most of the time—little disheveled as well? She seems right in her element, relaxed as if she is really enjoying all this.