He is actually correct about the possibility of real and hoaxes, but the question is why don't the so-called 'real' psychics agree to undergo scientific testing? The scientific method is merely a method to empirically verify the existance of phenomena and attempt to give an explanation for them, so if the real psychics did use the scientific method we would simply get better psychics.
Unless they're not real of course, that might be an explanation of why they refuse.