Why?
Because the name sign violates -- wait for it...! -- the school system's WEAPON policy. Yeah... the way his parents use the name sign, it kind looks like a VERY stylized gesture that is similar to someone firing a pair of pistols. And that's covered in the weapon policy. Seriously. The kids name is HUNTER... maybe the NAME itself violates the policy too. If not, maybe they need to tighten up the rules some.
Bloody people are NOT right.