aid to the civilian ppopulation is allowed as long as it is done under the authority of the blockading power. this is just long standing international law as restated in san remo convention and as affirmed by unscr regarding former yugoslavia among others. israel has every right to demand not only boarding and inspection, but also to direct ships to a designated port under her authority.
4.2-scale earthquake felt in Dead Sea, Jerusalem area (Haaretz)
from the article: Netanyahu: Israel will not allow flotilla to breach Gaza naval blockade