Apparently the American authorities thought so too. Otherwise they wouldn't have detained him.

Knowing a lot of Americans in their late teens and early 20s, I believe that his travelling patterns reflect a young man from Philadelphia who really had no idea what could happen to him, and who was possessed of the twin gifts of youth: a belief in one's own immortality and an overweening confidence in his own ability to get himself out of trouble.

Nick Berg's dad is angry at the American authorities who detained his son. I understand this. He's grieving, and is angry at everyone connected with his son's death. One of the first statements I read about the Berg family had to do with Berg's parents begging him not to go to Iraq. Presumably Mr. Berg was also angry at Nick, at first, for deliberately putting himself in danger, but it's hard to be angry at someone you love at this stage in the bereavement process. Someone has to absorb this particular type of anger, the "you should have known better" anger. The American authorities were supposed to be looking out for Nick, so they will bear the burden of his parent's anger, regardless of how well they exercised that responsibility.

One must always look at claims of conspiracy, because conspiracies exist. I have looked at this claim, and remain unconvinced. Come back when you have something solid.