I'm sure the delights of an unscheduled residency in the Lubyanka would seem sufficient deterrent for any unauthorised release of information.
Do you believe that KGB will chase leakers, then firing squad will shoot them, play balalaika and feed remnants to bears at Red Square? o.O
There is a lot of people involved into this investigation. Also aviation community is quite close and rumors circulated inside amplifying with each circle. I think that this "second" leak about "pilots disagreement" based on "transcript" published by 1tv after preliminary reading of CVR.
BTW MAK published
short report on accident (in Russian).