I understand your point LeadSled and totally agree. Most operators also have exemptions to operate into aerodromes with unserviceable slope guidance so the same argument could be applied to the influence of CVD on PAPI.
My comment however was in relation to that of cockney steve's.
The issue is, "if colour-generation fails, the display becomes greyscale."
(which, apparently,is exactly what CVD people see, anyway.)
We don't need to create wrong impressions here.