Glen,
A question if I may ask as I don't have the requisite knowledge/understanding at this time. It comes to mind after reading your recent posts. If I've previously missed something, my apologies in advance.
At the time that the CASA Regional Manager wrote 'THAT' email to your employer, did you hold any kind of instrument of appointment from CASA ? Maybe my terminology is dated as I've not worked in the civil system of airworthiness management.
Or was it that case that you were a person nominated in a critical role from an airworthiness/safety perspective in that organisation's procedures and processes pursuant to the applicable regulations/roles that applied to the flying school sector ? I'm more familiar with the latter personally, where the airworthiness regulator satisfies itself that the people an organisation nominates in key roles are suitable/acceptable. Note that the organisation 'FIRST' determines that it is so.