No. A coin cell wouldn't be used for anything more complicated than keeping a simple real time clock chip powered. Is it possible? Sure, with a level of engineering effort that would far outweigh any possible benefit.
If they had something fancy they wanted to do on battery power, they would stick in a Li-ion battery, which they didn't.
I guess I wasn't super clear. Also, obviously the system is powered on when any disc reading is happening.
I was thinking about the issue with key expiration dates and validation. It's not a good user experience to force users to enter the current date every time they boot their offline system.
If they had something fancy they wanted to do on battery power, they would stick in a Li-ion battery, which they didn't.