Curious, what does an LOA give you? I dont suppose you get paid or still get health insurance. Is it just a stopping of payroll/benefits and resuming it once you are back?
Legally, I guess it depends on the state and country. If a company approves a LOA but changes its mind, perhaps that would be counted as a termination and make the person eligible for severance, unemployment, etc. I'm not a lawyer and this is tricky stuff. But from a human perspective, there is some expectation that HR or the manager would try to help the employee return back after the LOA.