it becomes the first nation on earth to avoid civil war by allowing its military to rape prisoners

If this is true, it is only because usually the rapists got their way before enough people heard about it for it to become a civil war. Soldiers threatening mutiny unless they were allowed to rape people is a pretty common phenomenon in war.

Incidents like this almost certainly took place during the US American occupation of Okinawa, there just weren't smartphones to relay the information to the general public, other soldiers, and the government so they could take positions. Maybe the prisoners will be tried at a later date, like the US did with some rapists in the US armed forces.