"Here's the deal. Fucking someone, drunk, unconscious, whatever, takes conscious thought and effort. A guy's dick is NOT a force of nature, like gravity. It will NOT magickally take over his body and go pounding away at the nearest bodily orifice because the poor baby can't help himself when presented with an opportunity.
If some shithead takes advantage of a drunk/helpless/scared person and fucks them while they're unable to defend themselves, he's the responsible party in that situation, plain and simple. It doesn't matter if he's some bully with a gun to her head or some coward who puts a roofie in her drink. When one party is helpless and something happens, the one who isn't helpless carries the blame by default.