Two things occur to me
"Women love chocolate more than password security"
I know several women, some of them quite well, and my impression is that they love chocolate more than almost _anything_
"Little attempt is made to verify the authenticity of the passwords, beyond follow-up questions asking what category it falls under. So we don't know whether women responding to the survey filled in any old rubbish in return for a choccy treat or handed out their real passwords."
I know which I'd put my money on, because (although I do not have the privilege of being a woman myself) I know exactly what I would do. I would think "Hmm, here is a man who will give me free stuff, (chocolate even!), if I am prepared to utter some utterly unverifiable random word or phrase. Score!"
And I would go about my day, happy that the man had gone home pleased with his survey results (which were wrong, bwahahahah) and enjoying my new found chocolatey wealth.
So yes, I think what this survey probably measures is the number of people prepared to engage in some mild deception of a complete stranger in order to get some chocolate.
Further, I rather suspect that the people who didn't do so probably had some understandable issues about taking sweeties from clipboard wielding strangers. The figures probably reflect a rise in those holding such concerns, what with "the current climate" of worrying about [what ever it is this week].