Social anxiety is a symptom more than it is a disorder in itself. Also, this site isn't necessarily restricted to those who have social ANXIETY, but people who just plain socially inept/frustrated as well. You're definitely going to find narcissists as well as other predatory personality types among the boards just as you would the normal population.
But, no, I don't think there is any special link between narcissism and social anxiety. This post feels more like a dig at someone than a legitimate question.