I'm not sure how one is supposed to take this seriously. Israeli spokespeople first come out with some heavily edited chunk of audio and say the transmission came from the Mavi Marmara, then they admit they edited it and say it came instead from the Defne Y, but the voice comes in briefly amid transmissions and is never heard from again, the only voice identifying itself as actually belonging to the flotilla makes a perfectly simple statement regarding the illegality of the blockade and their intent to port in Gaza. We're supposed to believe that a) Israel didn't further manipulate the audio in their weird campaign to link the activists to Al Qaeda, and that b) amid all the random chatter going on in the background we somehow know the voice belongs to one of the activists.
They were 75 miles off the coast of the Levant using an open channel, the voice could be any jackass with a radio. It wasn't that long ago that a similarly anonymous voice worked up a wave of hysterical propaganda against Iran, until the Navy finally acknowledged that whoever said "You will explode", it wasn't an Iranian boat but just the random racist noise on VHF.