I think you have it a bit turned around. If I have a right under my country's laws based on my citizenship, my right doesn't cease to exist because I leave the country. For example, I continue to have 5th Amendment rights outside of the United States. Reid v. Covert, 354 U.S. 1 (1957).
I haven't read the decision that requires Apple to open up its devices to third party stores, but if that decision is somehow premised on rights conferred by EU citizenship, then the passage you quote would be valid.
I haven't read the decision that requires Apple to open up its devices to third party stores, but if that decision is somehow premised on rights conferred by EU citizenship, then the passage you quote would be valid.