National (or state) governments that disarm their citizens have a reason for doing so. Those governments are corrupt and abusive of the common citizen. They fear an uprising, so they try to prevent that by denying the citizens the means with which to do so.
If they're not a citizen, then they have no right to have an opinion on how this country is run. If they are it's regardless as they can't possibly have a logical reason to ban them as has already been pointed out.
Generally, people from countries that prohibit the citizens from owning/carrying weapons also brainwash them into believing that only people with evil in their minds would want to have guns, and that the people in general should rely on the police, and otherwise be willing victims. Sort of like Mas Ayoob said, "they believe that resistance to crime is immoral".