No, even if the order was to kill bin laden regardless of his actions, such an outcome still would be completely within the rules of land warfare. A criminal/terrorist has no right to any protections. They are able to be killed with predjudice. The only caveat would to be capture for intell exploitation, but then again, I think several three lettered US entities (DIA, CIA, NSA, etc) have been watching/listening for sometime...
There is no due process for such persons, nor should there be.
Regards;
Bump.