I was amazed by this too. I caught the end of a report about it on the radio and wondered what on earth she could have done or said to set them off (not that anything would have made it ok obviously but I was just wondering). She campaigned for women to go on banknotes! Just how pathetic are these men? It's astonishing. It's really clear to me that they don't just hate women, they FEAR them. They get their pants in a massive twist if a woman basically dares to do, be, say or in any way exist in a way that's not according to how these misogynists think they should.
However I don't think the issue should be rules about twitter or the internet. Sexist abuse and threats etc. should be made a crime just like racist abuse and racially aggravated assault etc are. If you take any instance of a sexist remark, attack or unequal situation and replace the role of the woman with a black person, it's instantly obvious how massively unnacceptable (and rightly so) it would be. Any kind of sexist victimisation should be made illegal in exactly the same way.
I don't think all men are like this but I do think that this isn't just extremist nutters. I know a lot of men who are deeply sexist, but "nice" on the surface, but if they thought they were anonymous or among like-minded friends might well give free rein to this stuff. I think greer was right, men's hatred of women is very big and very powerful.