hi doma,
i think you don't understand mach numbers!
mach numbers are dimensionless. the shock wave is the same at different altitudes so long as you fly at the same mach number.
this is why the manufacturers define the air frame's limits using a mach number.
it may not sound like common sense. but it is what it is.
once you know this, first you understand the plane was capable of flying at the recorded velocity, then that there was no conspiracy, and then that the universe is random rather than controlled!!
that is, unless the desire to believe in conspiracies is the fixed point to which all your theories are tethered.