He believes this when he has free reign to believe it. Something which has occurred to me is with how susceptible he is to believing just about anything, wouldn't that also work in the reverse? His delusions are a product of suggestion and reinforcement. Isolate him from that environment, feed him nothing but reality and maybe some of the damage can be undone, at least until some sped gets a hold of him again and convinces him he needs to return to CWCVille immediately to rescue it from impending interdimensional laser bombardment.