Those two things taken individually aren't bad at all (all things in moderation), but I think combined they tend to be bad news and I feel, given his history, Peter would feel the same way. I can't see him turning to alcohol to get out of an awkward social situation, nor can I see him being the type who is into casual sex. A 'simple' lapse in judgment it may be, but it's not a mistake I can see Peter making given its potentially serious consequences.
That said, I do think you may have a point. I feel that Peter should be behaving more responsibly than he is, but a screw up here and there, even a serious one, is to be expected. This is a man who occasionally lashes out in anger, has a history of cutting off his nose to spite his face and, if we're looking for a specific example of a moral failing, once slept with a married woman. Giving into more base instincts is not something he's always above. I think more people would be more inclined to see your point of view if it wasn't part of the entire BND package. We should expect to see Peter stumble occasionally, but the trend of writing him as a novice hero involved in sitcom style antics simply grates. That, combined with issues of dubious consent, accusations of misogyny and the cliche story telling tropes, makes the drunken one night stand an obvious and understandable source of contention.