Well, I guess as a foreign national, he got the firearms on the black market, without going through a background check.
So, if he did go on a rampage, they would call for background checks?
Since he has a residence here in the U.S., he is likely a legal alien with either a H1B work visa or green card. If that's the case, it is perfectly legal for him to purchase firearms.......
Seems to me the only law he broke was not declaring the body armor, and to be perfectly honest, I never knew such items had to be declared at customs either.
Since most stuff is made in China these days, it was probably cheaper to purchase it there than here.......LOL!