Me: Hey, is that Patrick Stewart?
Me: Was he the one who turned into the dragon?
Him: No, but he was Boromir.
Me (confused): No, Sean Bean was Boromir.
Him: That's what I said.
He takes the stance that the antecedent of his "he" should be understood as the closest preceding nominative noun (in that case, the phrase "the one who turned into the dragon"). I argued that 'he' doesn't switch away from meaning 'Patrick Stewart' until another topic/subject is explicitly introduced -- if he had said "No, but the dragon guy was Boromir... He did a great job," it wouldn't have been a problem. Or if he had emphasized his "he" -- "No, but he was Boromir" would have been another signal that the "he" had changed.
Antecedent-tracking seems to be a pretty complicated task. Which of us is closer to correct? I tried googling, but all I could find were exercises on pronoun/antecedent agreement.