If for WHATEVER reason that is not the case, the airport reverts to UNCONTROLLED.
Lets have a look at the FAR that states "for whatever reason" then. Where is it? Somebody post it or a link to it.
Who decides it's now "uncontrolled"? TRACON guy? You? Bob? Who makes that decision? None of the above have the authority do they? Maybe that's why there are promulgated times for operating and not operating towers no? So everybody knows.