Brits have a foreign central bank governor and they seem okay with that, if anything he's absolutely brilliant according to me. It's also the first i've ever seen a country use foreign talent at such a prestigious role.
When setting laws for something of such magnitude there is a clear conflict of interest. They are negotiating against a plethora of EU countries who have lots of people working in academia. A British citizen-only would not have a conflict of interest as such.