What Primis Richtofen picked up from the body was not the "radio" from Ultimis Richtofen's uniform, so he could communicate with Groph in Der Eisendrache?
But I think this conflicts with the idea that the Zombie Richtofen from the comics is from the body of The Giant, since you can see that he still has the radio.
Unless it's Treyarch's mistake, but knowing how careful they are with details may not be the case.
Also other points I would like to point out about The Giant are two initial quotes from Primis Richtofen in solo.
These seem to be