That's the same as saying that European based FedEx crews flying European based N reg aircraft with US licences (or any other crews with third country licences) would need EASA licences. Surely illegal for EASA to demand this, if so what about reciprocity and the FAA, Transport Canada etc demanding all pilots flying into their airspace having an FAA, Canadian etc license.
How about Aircraft manufacturers and their support pilots ? They sell a plane to Europe and can no longer offer a support pilot as they need an EASA licence ?