I think the young man's T-shirt expresses contempt. That's not necessarily the same thing as expressing hatred. The only way such a shirt could incite hatred would be to incite hatred against the person wearing it. That's not a crime, it's stupidity on the wearer's part. Trust me, nobody felt the least bit compelled to go burn down a church after reading the message on that T-shirt.

Furthermore, the shirt didn't say something like "Jesus is a cunt. Mohammed is the true prophet." Its message is nihilistic, not antagonistic. Last time I checked, nihilism was still a legal worldview.