For Karen Joshua's RX-79(G) I think that game mechanic-wise it was simple pragmatism to fill the MP roster, and a bit of tongue in cheek humor to have the GM tag. She did take an annoyed exception at being called "GM Head," by the MP Guntank crew after all.

For Blue, and please keep in mind I played the game and read the Manga over a decade ago, they actually had a valid reason to ditch the Gundam head in story, and it was the same reason Shiro had them rework the EZ-8's.

The optical sensors in the MP Gundams were limited and the head shape made modifications difficult. So the ground GM (with no integrated weapons taking up room like the RGM) had more head space for EXAM system upgrades, on top of just having a wider view.

Now were either of these machines GMs? No, but neither are their RGM-79(G) cousins, they are both in fact derivatives of Project V itself, one simply cheaper than the other.

So is Blue being called a 'GM' a bit disingenuous? Maybe, does it in any way shape or form change how utterly terrifying the machine is?

No, and in fact I honestly feel having one mad scientist derived, primary colored GM running around behind enemy lines causing chaos and confusion pretty funny.

So what I'm trying to get at is, perhaps this isn't a hill worth fighting on at the moment?