It fails the first test of legality i.e. naval blockade is part of the Laws of War and, therefore, there must be an armed conflict before a navy can legally blockade ANYTHING. When that flotilla set sail for Gaza there was no armed conflict; operation Cast Lead was already over. Israel can no more blockade Gaza because it doesn't like Hamas than it can blockade Tyre because it doesn't like Hezbollah.
At least 19 killed, 250 rescued after trains derail in India (AP)
from the article: U.S. scrambling to prevent Israel-Turkey ties from worsening