There was a time when I would've been the one writing that comment, so I know what you mean. It is frustrating for meek guys (I count myself as one too) to feel like we're being called out along with harassers. But ultimately I don't think what you're saying is accurate.
It took me a long time to realize this because I didn't have very good data to work from--I didn't have a large set of observations of interactions between men and women, and out of those I did have there were very few instances of harassment. It seemed to me that based on the complaints of harassment vs. the small number of cases I'd witnessed, the problem must be that women were choosing to call normal behavior harassment when it was unwelcome. Which I think is your argument. But I've realized that that's not the case. The kinds of harassment being complained of are not borderline cases. In most of the recent cases I've read about (Readercon, etc) the harasser was explicitly told to stop at least once. That is not ambiguous, and it's not based on the perception of the person being harassed.
I guess what I want to say really is, 'stop feeling threatened by this.' If you are a person with even a barely-functioning social instinct, and recognize and respect when someone feels uncomfortable in a situation, there is only a microscopic chance that anything you do will be misinterpreted as harassment. And if you do say something that someone interprets as sexist, the first response will simply be to call you out on it. That's a conversation it's ok to have if you're confused, 'I'm sorry; I didn't mean to offend you. Could you tell me what about what I said bothered you?' Again, if you're a person with a basic social instinct, you will prefer to modify your behavior in small ways to make the people around you comfortable. If you truly feel someone is being unreasonable, just avoid them.