Why go to all the way to Lebanon, and not the nearest US military site?
Seems like there were much closesr sanctuaries.
He had family in Lebanon, IIRC. Not that it would have been better for him to try to find a U.S. unit in Iraq - it would have - but it wasn't totally unreasonable to go to Lebanon.
No matter what, I am confident that the Corps was and is looking very closely indeed at this incident.