The State department can declare him persona Non grata.
IIRC, only credentialed diplomats can be declared persona non grata by the State Department.
A citizen of a foreign country can be banned from entering if it is determined that he/she is a threat to the interests of the U.S. But in this case there are always political considerations; Obama & minions would love to have banned Geert Wilders on 9-11 but feared a backlash.
Is this British kid’s name now going to be added to the TSA’s terrorist s***list?