Assuming they are similar levels of drunk, one party didn't get them into that situation specifically do that without the other one's knowledge, and they're both sloppily initiating drunken horny on each other, then sure. But really it would be worthwhile assessing the situation afterwards to see what actual harm/trauma has happened. I say this as someone who has drunkenly initiated things and its either violated a boundary or I've regretted it later.

I think the idea of having consent as this hard line, unforgiveable sin thing is probably not a good way of viewing consent. It's kinda puritanical. (e.g. most jobs are non-consensual in a puritanical sense, I would not be doing most jobs I've had unless I needed cash for rent/food, but we also learn to forgive people who help us get jobs we wind up hating. Also consent isn't just for sex)

The latest episode of the podcast Multiamory, which is focused on polyamory stuff but this episode was more general, actually has a broad discussion on this if you want to check it out. I disagree with a couple of points here and there, but whatever.