True. Although I find it hard to picture the father taking a body out to sea (or elsewhere) in full daylight, not knowing when serious inquiries as to the disappearance would be raised.
Scott Peterson took a body out into San Francisco Bay, which has far more traffic than one would expect in Aruba. Additionally, PvdS might have disposed of Natalee's body in the ocean on the North side of the island where less people are present.