If Rebecca had just said, 'guys don't do that' as PZ suggests that she did, then it probably wouldn't be such a big deal. But she didn't leave it it there. She referred to her talk on sexual harrasment and said even after all that, this guy still didn't get it. So she was likening his action to harassment rather than simply inappropriate.
In terms of sexism, the worst e-mails and comments that Rebecca gets are those that threaten her with rape or suggest she "needs to get laid" as well as those that belittle her based on her sex, suggesting that as a woman her opinion is of less value. However, there is another class of sexist comment which is what I'm going to call the "sexual compliment". This can go all the way from lewd and graphic propositions (sometimes with pictures) to joking proposals of marriage. What they all have in common, even the most ostensibly polite ones, is that they view her primarily as a sexual entity. Rather than treating her as an intelligent human being with worthwhile opinions, so many of these correspondents also feel that they have to add (implicitly or explicitly) that they'd be interested in having sex with her.
There's a tendency among men to believe that she should be flattered by this attention, but there's really nothing particularly flattering for a young woman to discover that random guys off the internet would deign to have sex with her.
The guy in the lift was of the same type. He presented nothing of value, only his desire to have sex with her. No woman with any self-respect would accept such an offer, so it carries an implied insult. He compounded this insult because he had listened to her ranting passionately about this earlier in the day, and had chosen to ignore it.
And is there some validity to the argument that this doesn't really do much for the wider movement?
Yes. If women are made to feel uncomfortable at atheist events, they will stop attending. If women go to atheist events and see very few other women there, they are likely to feel uncomfortable and will stop attending. These women are likely to have useful skills and valuable opinions, and without their input we are poorer as a group. They are also likely - and here I may be courting controversy - to have a different perspective to men. Broadly speaking, women see the world differently to men, and are likely to have different skillsets. Thus, by losing them, we are not just losing numbers, but valuable viewpoints and areas of expertise.
The other interesting thing to come from this is that it shows how difficult it is to have a conversation about this stuff. The reaction to Dawkins' commments went way overboard and stifled the opportunity for a real debate on the issue.
Agreed. It's an emotive issue and the division seems to fall largely along gender lines. Men don't see what the big deal is, while women find the man's behaviour totally unacceptable. This should tell us that, as men, there's something we're not getting. We need to realise this and work on it. Women too, need to realise that men just don't get this intuitively.
It's not so much about debate, as there's really no point in men proving that they have the right to proposition women in this manner if women still feel uncomfortable when it happens. Unless you're an asshole you don't want to make strange women feel scared or vulnerable, so you will make reasonable adjustments to your behaviour to avoid doing this unnecessarily.