Katie Moussouris (https://twitter.com/k8em0) is, unsurprisingly, spot on with the problems from her experience. Being able to verify that people trying to get into your room are indeed hotel security is a perfectly valid request. Trusting an ID badge is always laughable, but even more so in an environment like Defcon. While the privacy concerns aren't invalid, the safety issue posed by this policy are much more concerning.
If a woman is worried about being put into a situation where they feel they are at more risk of assault/rape they should be listened to. Its a shame that is being drown out in favor of the invasion of privacy narrative.