I'd say that you'd have to read quite a bit into the plate to say that it encourages violence, since there's certainly a leap between seeing a Haji and wishing him harm. The word "Haji" refers to someone who has made the "hajj", the Islamic pilgrimage to Mecca, which hardly qualifies as vulgarity.
Read the story at Fox News.
On a personal note, the first "Haji" I ever heard of was a character on the TV cartoon show Jonny Quest. The young title character had an Indian sidekick named Hadji, who in one episode appeared to have the ability to teleport himself.