I theeenk PC was being amusing there, with the ism?
It's not completely exactly a pedantry point, and it's more a moral tautology than a semantic one, but dh & I collect [ponces that we are] examples of things like those ads for ambulance-chasing solicitors which make a point of solemnly announcing "All lawyers authorised by the Solicitors Regulatory Authority".
I think it started with one for a pawn-brokers that said "guaranteed honest valuations".