[edjrage]

Sorry, but this is absolutely wrong and potentially harmful to your son if you eventually convince him. It is absolutely possible and not that uncommon for a neurotic person's mind to go blank when under considerable stress, at the point of forgetting otherwise completely trivial information.

I urge you to not dismiss your son's complaints but to instead investigate them further, preferably with the help of a professional therapist, to save him from the possibility of escalation of his problem.