There are 4 reasons to prohibit something
1. Be a handgun that is too short (not a handgun)
2. Be cut down (factory gun so not a problem)
3. Be full auto or converted (might be problem)
4. Named Variant (not a problem)
If the first version was rejected they most likely changed the internals to make it more difficult to make full auto, and if they are aiming for non-restricted .22LR then make the OAL 660 mm as the original is 640 mm.
The 9mm version will most likely be a Restricted rifle as I don't envy GSG in making a 18.6" rifle barrel.