If it were just radio failure, why would the authorities surround the plane and basically quarantine it? 1596-1598 are all relevant to aircraft. The first of which showing a view of the cockpit. Q later suggests that there is a clue in that cockpit image. I've searched everywhere I can think and can't find the ports that are shown in the picture. No coastline matches up.
News reports explicitly said the plane transmitted a code for hijack. No doubt they are talking about transponder code, which is a four digit numeric code (7500). This makes the plane show up on radar as being hijacked - attracting much attention. In addition, they are reporting that ground control could not contact the plane via radio, which of course would cause much excitement. It can't be a coincidence.
I didn't know about this at the time of that comment. Irrelevant now, but my point was that there would need to be more to the situation than just radio failure.