Pro-Israeli sentiment aside, this was a major boneheaded move by the IDF.
How about they first do a blockade, then send a representative to the ship to meet with the captain and discuss boarding to do a general search. You play it out long enough so the international press can see there’s no “aggression” by Israel. If it checks out, it checks out and they go on their way. If there’s contraband, you go back to the IDF ship, keep the blockade and release a statement to the press on your findings and why you won’t let the flotilla proceed.
Killing “aid workers”, whether they were or not, is perceptively one of the worst things a military can do. It doesn’t matter what the truth is at this point, because the media will not let the truth surface.
It's my understanding that's what was done, the search to be done in Ashdod, humanitarian goods then to be shipped to Gaza. The blockade has been ongoing for several years now, as has Egypt's closing of the border.