Nice attempt at spinning, but utterly stupid.
At the time that Giuliani called for national gun control, he did not know where the gun was purchased. And gun-grabber Giuliani NEVER mentioned what you just did about non-residents being prohibited from buying guns - he just said that the incident should be used to call for more national level gun control to include the legislation being pushed by Clinton at that moment.
those were the facts at issue in that case. unless you think the 2A right also extends to non-citizen palestinian immigrants with no resident status or background checks.