facts
Have I got this right?
The secondary response disappeared, then primary return disappeared. R/T shut down.....
Did somebody continuously track the a/c after that..who...verified?
So, the a/ may have disintegrated, it may have dropped below radar cover.
Maybe Blind Velocity Speed (unlikely at cruising speed and altitude) or Tangential Fading. (Radar Type in use ?)
So who continuously tracked the primary return?
If it was not continuously tracked it becomes unidentified. Who then re-identified it and how ? A primary return way off the flight planned track ??
I don`t think so.