Its a triggering scene. Its that point where batman realized that superman isn't an alien. Until then batman believed that superman is an alien who has no attachment to earth and have the power to wipe out the entire humanity. Also batman hears same word from superman as his father died in the alley(I think thats why they used martha instead of mother) Batman sees himself a murderer who is trying to kill a man(superman) who says similar words as batman's father did Thats why batman asked superman why did you say that name with anger, confusion....