This isn't about the evac. The PIC made his decision. The CMO office would have reviewed the process for compliance. If they had issues with that, then there would be a number of paths to head down from case closed to taking issue with the procedure itself, the PIC, the FA's and anyone else who touched the issue.
That Allegient fired him is an internal company decision. The courts will determine if the termination was appropriate or not, not the FAA.
Before you rush to reply, ask yourself why this isn't in front of a NTSB judge if you think the FAA has jurisdiction.