You're conflating a few different things here. There's seduction ability, which is its own unique set of skills (it's very possible to be good at seduction but poor at social skills; some of the PUA gurus fall in this category). There's the ability to pick up social nuances in real-time, which is what people with Aspergers tend to learn slower than others (though no one has this "naturally"; it has to be learned through experience). There's knowledge of specific rules, like "don't wander around naked". And charisma or magnetism is essentially confidence and acting ability. These skillsets are all independent: you can be good at some and poor at others.

Interesting, I wouldn't have said that they were as independent as you make out. I'd say it is unusual to be confidant with good acting ability and not be able to read social nuances (how do you know how you should act?). And confidance is definately part of the PUA skillset. Apart from that I'd agree, there are different levels of skill.

When sober he was fairly good at everything. He would steer the conversations where he wanted, generally organise the flat to his liking and not do anything stupid like going around naked. If you looked at our interactions as a group, he would have appeared the Alpha.

His excuse for wandering around naked was that he thought he was alone and that he should have the right to go into the kitchen naked if he wanted to. I.e. he tried to brazen it out. That might give you some idea of his attitude, what he expected to get away with and that he had probably gotten away with it in the past.

Apart from the lack of common sense (when very drunk), I think his main problem was underestimating people or at least not being able to read them. He was too reliant on his feeling of being the Alpha to realise his position was tenuous. No one was relying upon the flat as their main social group, so no one cared about him being Alpha of that group.

Well, of course not. For instance, if you punch someone in the face, they'll get upset regardless of your social skills in other situations. What this guy did was similar (though perhaps less extreme).

You might get upset but still not be able to do anything against the Guy. See Highschool.

(I'm also confused by the suggestion that being Facebook friends is a measure of intimacy.)

People use Facebook in a myriad of different ways. Some people friend everyone they come across, which means their friends lists gives little information. Mine is to keep an eye on the doings of people I care about. People I don't care about just add noise. So mine is more informative than most. Mr S. is very promiscuous with over 700 friends, I'm not sure about the other two.