Walter
If, as you claim, CPLS was fitted to ZD576, then that would demonstrate a fundamental airworthiness failing, because the regulations require every piece of kit to be listed in the RTS, along with level of clearance and any limitations. If it is not listed, it is not cleared for use to any level - the risk being, in this case, of EMI.
Care to list the equipment mentioned in the RTS? No sign of CPLS? Then there is a conflict between your assertions that CPLS was fitted and airworthiness is "waffle". In fact, the (lack of) airworthiness fact is key to your theory. Your theory may turn out to be wrong, but the fact remains.