We all have impulses we don't act on. Those impulses are no more our true selves than any of the other dozens of things pinging around our brains at any given time. Alcohol depresses higher order cognitive function which means that someone is more likely to act on an impulse they'd normally suppress, especially when they're really drunk.

But again, that doesn't mean the impulse is somehow our true self or what we actually want, or that the things people say three sheets to the wind are necessarily their true core beliefs. It's just whatever pops into that persons head at the time without the higher order parts of the brain stepping in to regulate that.

Which is not to say you should necessarily forgive a person for acting shitty when they're drunk. And there's nothing to ever excuse sexual assault. But the idea that alcohol somehow reveals the true self just really isn't true.