I am not a person who has a great love for guns. But then again, I do not believe that guns are the reason people die. They are the tool.
Your question is -
Given the parameters above, what arguments can be found to deny such a person ownership?
My answer is - none. However I would also add, that this being the case - I would also say that even if the person had a criminal records, or psychological/psychiatric issues, who doesnt pay taxes, may be seen as an irresponsible citizen, should also be allowed the same rights.
After all, it is the right to bare arms.
Peace