http://www.icrc.org/web/eng/siteeng0.nsf/html/57JMST
(c) vessels granted safe conduct by agreement between the belligerent parties including:
(i) cartel vessels, e.g., vessels designated for and engaged in the transport of prisoners of war;
(ii) vessels engaged in humanitarian missions, including vessels carrying supplies indispensable to the survival of the civilian population, and vessels engaged in relief actions and rescue operations;
(d) vessels engaged in transporting cultural property under special protection;
Read the Remo more thoroughly: they were not vessels engaged in humanitarian missions
granted safe conduct by agreement between the belligerent parties. (ii) is a subsection of (c), requiring that Israel
recognize the ship as humanitarian and agree to grant safe conduct, which Israel did not. You would do well to catch up on the law before bringing your weak takes on it.