I don't know about that - he's got a signed confession to a crime that an innocent man is about to be killed for. It's a pretty standard 'STOP THE EXECUTION!' moment - the only difference is that Superman can bust through walls. He's working within the legal system - he's just ignoring the legal niceties that, under the circumstances, would take up too much time and get an innocent man killed. Anyway, the whole 'American Way' thing aside, I don't think he's ever shown any particular favoritism towards America. He LIVES in America, sure, but he regularly responds to emergencies worldwide. During the 'Death of Superman' storyline, people all over the globe were shown weeping at the news and reminiscing about how he'd saved them or their loved ones from harm.