The way your post started, I thought you were going to tell me "it's not paranoia if they really are out to get you." I almost included that in my first note.
It's possible and probably worth it to mention, that he also may actually be extremely well medicated.
Psychosis/Schizophrenia is very real and affects many people, who can function very normally but think slightly weird thoughts and have the urge to express them and tell people.