Here's the whole problem with what you are doing versus "criticizing Israel"
You insinuate Israel went into this intending to slaughter activists. If you didn't feel that way why condemn the boarding at all? Activists get detained and arrested every day. What makes these ones so special?
What makes them special is they were killed because they went beyond the level of civil disobedience.
I read a few articles about this. In every one, the Israeli commandos were told there would be no resistance and this would be a simple 'arrest of protesters'. They get on board and these 'men of peace' attacked the Israeli troops, putting lie to everything they claim to be about. The Israeli troops were not mentally prepared for that sort of reaction. In other words, their intent when they boarded was no violence in the first place.
And that is why I refuse to condemn the boarding. Those troops defended themselves while following their orders, and until I see evidence to the contrary, I will not feel differently about this.