I don't think the issue is one of social incapability, but one of failing to match a hire with his responsibilities. If you're going to have your technical guy interacting with customers, then being technically brilliant but lacking customer service skills is not a good fit.

I work for MegaCorp. We have developers here that are incredibly difficult to get along with and a few that are great. There seems to be this sense that the more capable and intelligent a person is the more frequently they're jerks to deal with. I haven't found this to be true. There are plenty of good devs that aren't "holier than thou" (and one of the best devs I worked with was clearly on the extroverted side, though most of them land on the introverted side of things).

I will say, though, that more people have ended up being let go for attitude, rather than work quality where I am employed. To put it plainly, in a large corporation where you have to work amongst imaginary and real bureaucracy, it doesn't matter how skilled you are, if you can't work with people you won't get anything done. Your fantastic project/work will not be looked at because nobody will care to see it and your manager (often non-technical) won't want to show it off because you keep aggravating him or putting him in the awkward position of defending your behavior to his superiors.