Douglas Cooper didn't take Alston Cooper with him, which Sean Knight had anticipated.
Considering Alston's personality, if he had returned with the yacht, there was no telling what kind of trouble he would stir up.
Moreover, Sean Knight and his companions had all their documents in order, but Alston didn't. Once he got on the cargo ship, his things were confiscated, and Sean Knight and his team couldn't recover them.
Not just his, the ID documents of the other men and women weren't found either.
This trip was intended as a rescue mission. Originally, they hadn't expected any rewards at all.
Not every journey needs to yield something in return.
But to Sean Knight's surprise, they stumbled upon a treasure and obtained a large quantity of gold coins while rescuing some people casually - a blessing in disguise, indeed!