Why does the Jesus Seminar not invite scholars and historians of divergent views?

For example, as long as I've been a member of the professional societies, a very large percentage of the Society of Biblical Literature and American Academy of Religion have been evangelicals. Yet not one of them has ever been invited to join the Jesus Seminar, despite holding prominent university and graduate school positions and considerable acclaim. Is the Jesus Seminar just a club whose members are chosen by their agreeing with (and being old friends of) the leadership? Is it any surprise that the general public is never informed of how anyone becomes a member of the Jesus Seminar?