The penalties may seem harsh for a young lady but there can not be a double standard when it comes to security. Just because the remarks were uttered by a young western female does not warrant the excuse that they were just a joke (and 3 times???). Maybe some on this board would be less quick to jump to her defence if it had been a middle eastern male who had made that same joke?
Having had the 'pleasure' of going thru US security 4 times in the last 2 weeks, I will have to say that despite the added time and inconvenience (shoes off, laptop out, finger prints and photo) I was treated courteously at all times. Perhaps because I treated the people who were doing their jobs with courtesy too. It does not take much to play by the rules.
Whether such checks are effective or not are a different matter, but they do give me a sense of security (maybe false) when on the aeroplane. Much more so than if no checks were conducted at all. And when you are a frequent traveller, I think this counts for a lot.
My opinion anyway.