RetiredF4:
I suppose mr. Duncan Steel doesn't like to be reminded of that blunder he published on 2014 April 02, when he did not understand the interpretation of the logged BFO's. That was explained in the ATSB report "MH370 - Definition of Underwater Search Areas" dated 26 June 2014.
Your first quote doesn't have a date and does not mention BFO.
The BFO's for a northern route would be about 78 Hz greater than the logged BFO's in level flight. To obtain the logged BFO's on the northern route the aircraft would have had to climb at 3360 feet per minute during the 343 minutes of flight remaining after the first 'ping' at 18:25 UTC. That is 1,152,480 feet.