I don't think that there was any ambiguity. Everyone knows exactly what Trump meant.
Not so absolute, Max. Better to know some psychology. When a healthy man lies, he would not cheat himself but rather tell himself in his mind "You've lied." In this way he keeps healthy and carefully makes more lies to cover the original. A man who cheats himself would more likely become schizophrenic.
Trump lies everyday, but he's not schizophrenic. So he most likely doesn't cheat himself. He keeps telling himself "You've lied" or "You're a total con, Trump, I know you" to keep alert and skillfully dodging any responsibility. It is possible that he made a slip of tongue to reveal this secret.