It is actually a very good point that the licenses EASA is apparently requiring would not be legal by State of Registry rules (e.g. FAA 61.3) to fly the same aircraft. So on what basis will EASA determine what EASA licenses are required?
It is a bit like proposing maintenance oversight. A Part M company, with no FAA approvals or FAA qualified individuals, has to legal way to generate a release to service (or actually perform any task whatsoever) on the airframe or maintenance documents relating to it. So what exactly will they be doing??? Apart from merely asking for a cheque. In this I am referring to the latest proposal for oversight of ME TPs and jets.
With ICAO, you can't have it both ways.
EASA is entitled to require EU citizens (not residents) to wear pink underpants in EU airspace, but they have not published such a clear proposal.