You’re effectively arguing that there should be a civil aviation safety rule that says all people involved with any activity relevant to the safety of operations authorised by a certificate or approval must be employed under a contract of service with the holder of the certificate or approval and, therefore, not as independent contractors or any other kind of ‘non-employee’. Everyone must be on the payroll of the certificate or approval holder as an employee.
I don’t think the rules have ever said that and doubt they ever will.