As a 777 type rated pilot, I am pretty much 100% sure that the known flightpath after the loss of radio/SSR contact required a) someone still alive manipulating the AFDS/FMC and/or b) someone to have programmed a route totally different to the original flight plan prior to the loss of contact. Both are deliberate acts incompatible with the best interests of those on board. Make of that what you will.
For the aircraft to have followed the route it did, as opposed to what it was meant to, without any human intervention, would take so many extremely unlikely events in a continuous chain that the combined probability ends up so vanishingly small it can be effectively discounted.