Makes sense in Europe
A grant of approval in Europe (Ops, 145, 147 etc) is based on the company procedures meeting the requirements of the appropriate Part-XXX.
If your company procedures are more stringent than the Part and are accepted, then when you step outside of your procedures you effectively invalidate your approval (as it was based on your procedures).
As your grant of approval from the national authority is based on EU law then it could be argued that you have broken the law.
Is this the sort of logic that has been applied here?