The story has been too widely-published to be untrue. That being said, there is one thing which casts serious doubt on the veracity of the guard's story...
"Do you have the document that Saddam signed?
It’s in Baghdad. I can bring it in a week along with pictures that show how close I was to him. Those are pictures I got from him. I’ll give them to you. Because of my position, I could go anywhere in Iraq and no one would ask any questions. I used cars marked with his seal. I could get into any palace; few people could. I was very proud that my president treated me that way. "
If he is so afraid, why would he even THINK about going to Baghdad to retrieve the document?
He could be a Hussein plant to dispense false information...
Another thing...
If the guard actually exists (and, again, I could believe that he does), why hasn't this story aired on NBC, ABC, CBS, or CNN? Could it be their Anti-American bias?