Poor Martin Scorsese. When he made “Goodfellas,” he never thought he had to put in a scene where somebody told Joe Pesci it was morally wrong for him to shoot Spider. He didn’t bother to include a scene in “Casino” where Robert De Niro questioned the ethics of smashing a card cheater’s hand with a hammer. And in “Gangs of New York,” nobody stopped to talk about how bashing each other’s skulls might be considered antisocial.
He must have thought this was self-evidently bad behavior or something.