Of course it's important to recognize when it's actual misogyny and not just disagreement with the code.
Consider the method they used to identify gender - they based it on the email being linked to a Google+ account. This rules out most submissions made as part of corporate work.
So if corporate users submit better code than hobbyists then you would expect a drop. And you do see a significant drop across the board for gender-identifiable vs gender-indeterminate contributions.