Well that, and also there aren't a lot of options - I believe the list of DSVs that can reach the Titanic is Alvin, Sea Cliff (if it's still operational; I haven't seen an update since 2005), Nautile, Mir 1 (out of service), Mir 2 (out of service), Konsul, Rus, Shinkai 6500, three or four Chinese submersibles, Deespea Challenger, and Limiting Factor. Of those, none carry more than two passengers (with Deepsea Challenger being a single-occupant craft and Limiting Factor only carrying one observer) and only those last two are privately owned and not controlled by a government agency, military, or oceanographic institute. I believe the Mir submersibles and Nautile were the only ones that were ever "hired out" for private endeavors on the Titanic wreck.