It's because he was dressed like a Stormtrooper.
This isn't the hobby you're looking for. (via 7 News)
There's nothing wrong with buying an accurate Star Wars Stormtrooper costume and wearing it around town. You might get some stares, but that's probably what you want. There is something wrong with wearing it and loitering in front of an elementary school. That's liable to get you arrested.
That's what happened to this unlucky member of the Imperial Army. He appeared in front of Brickett Elementary School in Lynn, Massachusetts on Wednesday just moments before class was meant to let out. Parents there to pick up their children were shocked and afraid. They didn't know what he was going to do – he was holding a blaster, and they didn't want anyone to wind up like Uncle Owen and Aunt Beru. The principal noticed him and delayed dismissal until police showed up. Officers immediately arrested him and removed his mask, identifying him as a local man, 40-year-old George Cross.
Luckily, it turned out his laser gun was fake (because laser guns aren't real) and he claims his intentions were totally benign. He bristled at questions from 7 News reporters after his arraignment:
"Like I'm some kind of weirdo? I bought a costume, I was walking through the neighborhood showing friends, and then all that."
By "all that," he meant his charges of disturbing a school and loitering within 1,000 feet of a school. Those charges aren't even that bad considering his behavior. His story of "showing friends" is pretty sketchy. Are his friends 7? They would be the most impressed by the costume. If they're not, then why was he meeting them in front of an elementary school right when it was letting out? I don't think he was going to do anything bad – I think he wanted to get a reaction out of a bunch of kids. He just didn't count on the reaction of all the adults.
But what do you expect? He's a stormtrooper – they're famously weak-minded.