Let's assume they're right on this one- if that is the case, it sounds like something sinister happened. The equipment being shut off, the plane changing way off course headed nowhere near land but to a remote, pointless region of ocean. The scenario of a pilot murder/suicide still could fit within these parameters, it's almost as if perhaps one or both of the pilots incapacitated everyone, including themselves, the deed is easier done as the plane eventually goes into the drink. The most ironic part about this are the two apparently Iranian passengers with stolen passports who went through all the trouble to steal away for Europe.
Equipment being shut off screams that it wasn't something sinister. Imagine you were on the flight deck with the desire to end it all. Just do it. None of that equipment means a thing. Nobody can stop you. All they can do is watch, transponder on or off.
