Really? wow that is very stringent. For USNCO, could you just lie about your legal status and go to national level and nobody would know? I don’t expect to do that good at nationals so I don’t think they would find out.
I don’t know if my Test administrator does that…?
For example, on the USABO website, it says
“Each student must be a citizen or legal permanent resident of the U.S. and be able to provide proof of US passport.”
for the open and semifinal exam but they might not ask for the US passport.
Thanks