Stuff, I think not. If you are medically downgraded then passing the fitness test becomes irrelevant. The failure and discharge applies to those not medically downgraded.
My first case is sick, unfit, but not medically downgraded, so he can do OOA, is presently exempt fitness tests and, as a corollary, will not be discharged for failing his fitness test.
The other was in the process of remedial fitness training which was effectively put back 9 months during his OOA period.
No, failure might get you kicked out but it does not stop OOA.