He was not being an accidental asshole. It's not just about hurting a person's feelings. 140 character limit aside, there are better ways of expressing your criticism without derision, and its better for the community if we try to maintain some decorum.
Accidental asshole isn't a real concept. I highly doubt any of the people would have reacted differently in person, for example. The character traits that we ascribe as being an asshole are developed over many days, during which many of the reactions are intentional.
As the biggest one on TV (House) would say: "People don't change". This is one of the many reasons I can't stand being in this business. Computers tend to have a dehumanizing effect on people. Just the fact that people only see code and not the actual person behind the code leads to the kind of mocking that should be reserved for inanimate objects directed at flesh and blood.
Apologizing (or in this case, fake semi-apologizing) doesn't make someone less of an ass. They may have to "act" less of an ass in order to make the apology seem legitimate.
Not really. He's said sorry, unreservedly. He's explained that he messed up, and that it really wasn't what he meant to say at all. I think that it's fair enough to disagree with something, just the way you say it is important.