These laws do not protect those whose stated goals are to sail civilians into a hostile war zone for the stated purpose of aiding a terrorist entity and breaking a legal blockade that has been declared by a UN member state. It would be irresponsible to allow passage into a war zone where the safety of the passengers could be at great risk. Try leaving port with a stated destination of North Korea, see what happens.
Two Turkish soldiers, five Kurdish militants killed in attack (Reuters)
from the article: Gaza-bound 'Tahrir' crew warned ship may be in danger