Well, that might be an oversimplification, but... OMSBON NKVD was organized more like military college than actual combat unit. They saw action in November and December of 1941, but that's all.So even a simple rifleman in the unit would be a lieutenant? What about NCOs?
There were two categories: 'permanent' and 'variable' staff.
First ones were instructors, trainers, and commanders.
The second category were conscripts to be trained. After their training was over, they were formed into groups to go behind enemy lines or promoted into permanent staff.
Your PCs are part of permanent staff. So far, you were considered too valuable to risk you; but now High Command has other plans...