Even in the comics Superman wouldn't save someone if they didn't want him to. A man was on a ledge and Supes managed to talk him down, and afterwards heavily implied he wouldn't have caught him to if he'd jumped. Pa Kent told him not to expose himself because of his beliefs and Clark didn't feel it was his right to ignore his fathers choice.
Because Superman doesn't believe its his right to decide who lives and who dies and he'll only compromise that belief under dire duress like in MoS.
Or you know, when he just feels like a killin', like in Superman 2. 😉