He's been asked if it was for a story numerous times, he refuses to reply (and not story has ever come of it in the 18 months since it was taken) or simply insults those who ask or point it out. Not to mention its far from the only time this has occurred, rather he has a habit of associating with the Alt/Far right.
Well stand out contenders would be
Brittany Pettiebone (who posted the image on her twitter feed),
James Alsup (nice guy - member of a neo-Nazi group) and
Tim Gionet (another charming Neo-Nazi).
Calling the group Alt-right is actually being kind!