What is the scope of the probe? Is it to look at planning, policy or actions on board the ships? Bottom line is that Israel don't want anything even close to another Goldstone report and limiting scope and who probe can talk to will make sure it of that.
Israeli soldier collapses, dies from heatstroke during visit to Jerusalem's Old City (Haaretz)
from the article: Despite wider remit, soldiers won't be questioned in Gaza flotilla probe