Asshole is of course facetious, and I don't think anyone suspects any of the posters here of beating themselves up horribly about it, but the general sentiment being expressed is still one of regret and feeling bad, and for what? Because you assumed the sex of someone in an article and ended up being wrong? This doesn't hurt anyone, I suspect. I don't believe that the positive energy in the ether is going to suffer a net loss because some people made this assumption either.

But it's not just that, feeling bad about about assuming the incorrect sex of an author and recognizing a simple mistake. This can be seen in the fact that one poster even went so far as to describe their assumption and one of another user's as being 'sexist', which it most likely is not. Someone said it best earlier, so I'm just going to quote them,

'Making an assumption about someones gender, race, age, etc based on what is most common (or most common to you) does not make you a sexist, racist or agist. It just makes you human.'

When presented with a faceless author and no hints of their sex or appearance, its pretty typical for one to fill in the blanks in their mind. The picture they come up with will be informed by all the experiences that they have encountered in their lifetimes. Simply being wrong doesn't suggest any ill will, belief of inequality, discrimination, or prejudices towards or against any group of people. Whoops seems like a level headed response, Oh shit I'm being sexist seems like a bit of an exaggeration.

Although it totally could be case, and kudos to someone who suddenly has the self realization that they're a sexist and wants to post about it.