It's a very interesting proposal - I'd sit down with a lawyer and read the fine print.
I'd love to see the DC versus Superman lawsuit...
Later: A belated and very cynical thought - if Clark starts to do these things he will inevitably be associated very strongly with the USA. The government needn't ask him to go after terrorists - sooner or later the terrorists will go after him, and he'll be forced to take action to protect the people around him.
