SATCOM pings and ACARS data transmissions are completely independent.
The article states that the ACARS data transmitted included GPS coordinates from the plane. It doesn't matter how it was sent - the GPS coordinates were part of the data.
Those coordinates were then used to 'calibrate' the interpretation of the SATCOM ping sent (independently) around the same time.
Another try, and then i will shut up
:
To calibrate the signal path between satellite <-> A/C transceiver, you have to know the exact position of the A/C when a SATCOM transmission is made. My assumption - which may be wrong - is that precise secondary radar fixes where available until 1:21. If the SATCOM transmission, that was used to calibrate the signal path, was made at any other time than 1:07, it would make much more sense to take the secondary radar fix from the time of SATCOM transmission to calibrate the signal path.