group discussions are a requirement in our industry. if not wanting to talk to people is a mere choice then you should be looking for a job where you don't have to talk to people.
in my understanding, having difficulty or even just discomfort to talk in a group implies trauma. and they deserve any help we can offer. but if there is no trauma and they simply can't be bothered to make an effort to accommodate the group, then why should i make an effort to accommodate them?