"...But, his parents should give him a small camera that can be used discreetly to take pictures of Hillary and Sanders campaign attire..."
Read the article. The kid's hat was autographed by Trump, probably during Trump's visit to Fresno on 5/27.
He probably doesn't know about Trump's politics. But, he has a hat signed by a public figure. It's not much different than a jersey signed by a professional football player.