I was trying to not get into all of the minutia of citizenry and generalize. Permanent residents are close enough to citizens and IMHO, should have full rights, including 2A. Work and Student Visas I would not like to see in possession of firearms.
Also you are mixing up non-US-citizens who are just tourists and the ones who have legal permanent residency.
A legal permanent resident can legally buy firearms and even get a LTCH in the State of Indiana.