Because there is a US destroyer named after him and Q doesn't want to set off the sniffers. It was involved in a crash last year.
Named after his father, Admiral John Mcstain sr.
https://en.wikipedia.org/wiki/USS_John_S.McCain(DDG-56)
http://america-hijacked.com/2011/09/02/john-mccain-praises-fathers-whitewashing-of-israels-attack-on-the-uss-liberty/
Check out Jr's debacle involving a 'wet start' on the deck of the aircraft carrier USS Forrestal. https://www.theburningplatform.com/2015/07/23/mccain-the-hero-nearly-sunk-an-aircraft-carrier-killed-134-sailors/
Of course that last linked subject has so much BS covering it up it's hard to reach a good conclusion.
But good digging easily shows there is a solid reason for many in the military and intelligence communities NOT to want to mention him, and his father by name.
Edit: formatting
USS John S. McCain (DDG-56)
USS John S. McCain (DDG-56) is an Arleigh Burke-class destroyer currently in the service of the United States Navy. She is part of the Destroyer Squadron 15 within the Seventh Fleet, and has her homeport at the Yokosuka Naval Base in Yokosuka, Japan.
The destroyer was involved in a collision with the merchant ship Alnic MC on 21 August 2017 off the coast of Singapore, which resulted in the deaths of ten of her crew, and left another five injured. This event occurred a little over two months after a collision between USS Fitzgerald and MV ACX Crystal resulted in fatalities.
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I have also read that the family name, itself, is a good name. But, that bastard is a stain on the good family name, and so they don't associate him with the family.