

At least you laid out some actual facts here, not just believe me bro it’s a conspiracy.
Still flimsy assumptions here.
Just as much reason to assume he snapped and acted independently as a loner like you described and is the normal mo for assassins in the past. And that SS is still has gaps in their security.
https://www.atf.gov/firearms/qa/may-aliens-legally-united-states-purchase-firearms#%3A~%3Atext=An+alien+legally+in+the%2Cvalid+hunting+license+or+permit.