"for all the loss of comms/no comms conspiracy crowd I can assure you that if indeed this aircraft hit severe/extreme turbulence it is almost impossible to use the radios"
Not disagreeing with your general point but some headsets used to have a PTT switch in the headset lead - if you were a 2nd officer watching the other 2 pilots wrestle with a frighteningly vibrating aircraft you can hit that PTT and get your distress call off. (That was how, back in the 70s, I received a distress call citing extreme turbulence). Modern aircraft with a crew of 2 pilots only are far more likely to stay silent.