I don't think the show takes the standpoint that psychics are frauRAB - that is Patrick's view. Grace, for example, believes in them. Bruno Heller has said that he does not, but that his wife does, so I think he is deliberately not taking a firm view on the show in general.
I honestly don't believe that Kristina could be Red John. There has been a lot of evidence from both season 1 and 2 that RJ is a man so we would have to disregard all that evidence. And to lift that chair with Patrick on it would take considerable strength, so not only a man but a very strong one.