This is exactly consistent with the manual. I would also note that technically you are advised to turn off bluetooth during takeoff and landing. The language is not clear but that is what they are saying. And to do this you need to put your phone in airplane mode with bluetooth off and shutdown your receiver.
Unfortunately we have seen a number of reports of shutdown Dexcom receivers having an ERR121 and requiring replacement. And to be honest, you cannot turn off bluetooth on your transmitter which makes the guidance to shutdown your receiver strange. I mean they are both LE bluetooth, why is the receiver a problem and not the transmitter. I don't even know whether the receiver is actually doing any significant transmission.
Because of this I typically will put my phone in airplane mode with bluetooth off during takeoff and landing, but I just keep my receiver on. I will generally turn my phone back on during the flight so that I can use my wireless headphones to listen to books and music.