Most boats heading North will take the route the was taking. He was centered between the point and some offshore reefs.
All they had to do was wait for someone to come by or as you said they may have been drug or gun runners out doing their thing, just happened to come on it and said "Why Not". He was an unlucky 'target of opportunity'.
At least they didn't beat him up and kill him. We had friends in Venezuela back in 02 that were boarded. They tied my friend in a chair, threw a blanket over him and started beating him. He never had a chance to help them load their panga. They just came aboard at night and started beating him.
He told me later that he wouldn't have given them a hard time. They just wanted to beat him up and then take his stuff. Taking the stuff wasn't enough I guess.