Wufei is not anti-social. If he were anti-social, he would make a point of not speaking and evading when spoken to. Notice that whenever spoken to, Wufei does respond and he even voluntarily speaks (such as at New Edwards). If one wonders why he is so quiet during Operation Meteor, it is simply that he is a quiet person who says few words, but those few words always mean much. Wufei prefers to think things over rather than to discuss them; that's simply the way he functions and, one must admit, it is because of this that he is more aware of what is going on than his fellow Gundam Pilots (e.g. New Edwards in Operation Meteor).
One may argue that Wufei is anti-social because he did not want to join the other Gundam pilots until Wing Zero showed him the way. When Wufei finally does join the other pilots, he says he is doing so because it seems to be the best way to accomplish his goal of defeating Treize and Zechs. From this, one may gather that Wufei did not want to join the others because he sincerely believed that his goal would be accomplished more efficiently if he worked alone. There is no evidence that he didn't want to join them because he is anti-social.
And now for my personal rant--I REALLY DON'T SEE WHAT'S WRONG WITH BEING ANTI-SOCIAL!!! Those who are anti-anti-social are just afraid of being alone or they don't know how to think/discover great things by themselves. There are those who learn better in groups and those who learn better independently. Look at Thoreau--he was anti-social and didn't keep more than three chairs in his house because he didn't think the fourth person was worth it. And yet, Thoreau is undoubtedly one of the greatest thinkers that has ever walked the Earth. When I graduate from college, I want to be just like him--live in a little shack in the woods, next to a pond, with only three chairs and think all day. Give a man all the time in the world to himself and he will think things that no one else could dream of. Email me if you want to know more about Thoreau and his three chairs.