Slightly different scenario, but my cousin was born in the UK and therefor was a British citizen but was also an Irish citizen through his mother. He works at b

Slightly different scenario, but my cousin was born in the UK and therefor was a British citizen but was also an Irish citizen through his mother. He works at big defense contractor and had to get security clearance (pretty low level one). Because of his dual citizenship he is not allowed to work on certain projects. I suppose it might count as exporting classified information to a foreign national or something like that.