So now I need to know what was his pay grade despite his classification? In my little corner of the world (private sector) they cannot demote your pay because you got demoted.
During my years in the military, if memory serves, your rank was your pay grade. If you got busted from E-6 to E-4, you started drawing E-4 pay. Years of service couldn’t be taken away, and they meant an E-4 with 10 years service would be paid at a higher rate than an E-4 with 3 years service.