I wouldn't judge her as sheltered, i know people who have gone through some horrible things who are just the same overreact at the drop of a hat. but i sure as hell judge her as oversensitive. And your right everyone is offended by different things, I'm offended by her response to his joke in the name of all women. But so what. I'm just mildly offended, it shall pass.
I've been through my own personal hell and get 'uncomfortable' (ie offended) by things no one would ever think offensive. But is it my right to impose this on everyone around me? no. I have no right to dictate other conversations that are not directed at, nor about me because who am i to say what is offensive and what is not, its bound to be different then most.
She probably does not deserve the reaction shes getting, but then she made a really poor judgement that got someone fired for something they shouldn't have been fired for. Maybe next time she will think twice and exercise some self control before doing something so wildly inappropriate. (he acted somewhat inappropriately to, but she was far far more so by posting that pic)