Maybe there’s a connection to the Mexican cartels explaining the use of Spanish on the license plate and the name Diaz. This is just pure speculation but as long as the border remains open, it’s bound to happen sooner or later.
Could be, but bizarre as it appears, Diaz/Dias is a known first name in Kazakhstan.
"Terrorista" is not really "use of Spanish"; it is an internationally recognized word and the suspect probably thought that the ending -a makes it sound more sinister, or funny, -- who knows. Or maybe "terrorist" was already taken. What is Obama's license plate?