I think he genuinely suffers from depression and anxiety.
Powerlevel but depressed KiwiFuzz is perfectly happy to sit in her own stench for weeks on end all high on pot and being a general waste of space, whereas happy KiwiFuzz gets shit done.
Nobody is that much of a piece of shit without some issues.
I think perspective on this changes based on if someone's met anyone from Online before. There's a difference between knowing someone in your neighborhood as the annoying, screeching asshole and knowing someone on Twitter as the annoying, screeching asshole.
9 times out of 10, any Twitter idiot who's like Kevin will wilt like a moldy leaf when meeting people from The Internet without their usual gang of familiar companions around. A friend of mine actually had this happen years ago where she happened to be going to an anime convention or something where this chick she knew online was also attending. Said chick was caustic, the "I just tell it like it is!" type, the one who would be catty for no good reason just because that's who she was, sorry! Apparently when meeting her in person, though, my friend (who is extroverted, at least compared to most animufags) tried to drum up conversation with this girl several times. Nothing "third degree," to my knowledge, maybe shit about hanging out to get food or whatever.
Apparently the girl was so shy and timid that she couldn't hold eye contact, she sat on the floor away from everyone else, she fiddled with her clothing, etc, and faded into the background. Opportunities where she'd be expected to be searing against maybe some fat cosplayer were flatlined; she would fumble and shrug and that's that.
Point is, I don't think for a second that Kevin is some ultra confident "listen to me, IT'S MA'AM" type troon in public. He'd never present a confident front in any fashion. Just look at most if not all of the candid pics of him. He looks hunched over, awkward, and withdrawn. I wouldn't be surprised at all that he has some weird anxiety issues during situations he has less than 100% control over.