I'm not sure. Since you're meeting with a group of people who have the same trouble as you, there's no way you can fear rejection...
But from what I can see on that forum, even though everyone shares the same fear and/or disability in socializing, there's many different types of personnality here: depressed(even suicidal)- angry - sarcastic - sensitive - obsessive - all of the above - some seems more content and others have more success in some other part of their life. So maybe group therapy wouldn't work with people having too different temperament and/or background.
But we often see group therapy that makes progress when there's some friction between participants so different people might be not all bad also...
"It is better to remain silent and be thought a fool than open your mouth and remove all doubt. " -Lisa Simpson