While I'm a firm proponent that people should live their lives how they wish and choose, I'm also fervent that no one should have to tolerate inconsiderate and insulting behavior. Period.
I endorse the above message.
As many others, I have no problem with people having a few brews or whatnot during the game, but getting drunk or stoned rarely turns out well. That is, unless you're comfortable with the people you play with and their all happy go lucky when buzzed (like myself). Doesn't sound like that was the case here, though. Since you were just visiting it kind of limits your ability to do anything. Was it me, and depending on my mood that day, I'd have probably excused myself from the game.
The "that's the way he is" line is a decent explanation, but a poor excuse. Your friends shouldn't continue to put up with that. Being said though, arguing with drunks is pretty much an exercise in futility. They should catch him the next morning when he's dried out a bit and told him to knock it off or not to come back. Otherwise, its largely their own fault for allowing it to go on, but perhaps I'm just getting grumpy in my old age.
I've had an experience or two like this as well, so I can sympathize. In one case the drunk decided to show us all how to load his handgun at the gaming table . . . . yeah, and all I was thinking was how this would look in the news the next day if his trigger finger slipped
"ritual slaying linked to D&D". I had a talk with the player later and made it clear that that would never happen again. Fortunately, he knew he screwed up, and learned from his mistake.