Battlefields are glacier slow compared to games, vr, trading, data processing, etc.
Tell that to a missile radar system that needs to evaluate in in real time what the missiles it is tracking are actually going to hit.
Example the NORMANDIE ballistic missile tracking.
http://www.businesswire.com/news/home/20090302005701/en/Thal...
I have other examples, like battleship gun turrets computer aided targeting systems. You don't want the computer to stop for thinking instead of live tracking what those turrets are supposed to hit.
Military don't see to have any issue using real time Java to control weapon systems.
Aonix, nowadays part of PTC, has lots of customers. From missile systems to battle cruiser targeting systems.
So apparently Java real time GCs don't have any issue on the battlefield.