Florence, Arizona: Student suspended for having picture of gun on his computer

Can't schools differentiate the picture of a gun from an actual threat?  From Florence, Arizona:

A high school student in Florence said he has been suspended because of a picture of a gun.
Daniel McClaine Jr., a freshman at Poston Butte High School, said he saved the picture as his desktop background on his school-issued computer.
A teacher noticed it and turned him in.
The picture shows an AK-47 on top of a flag.
McClaine said the school initially suspended him for three days Friday.
. . .  the district policy states students are prohibited from “sending or displaying offensive messages or pictures,” and cannot access, send, create or forward pictures that are considered “harassing, threatening, or illegal.”
McClaine said he read the guidelines but does not consider the picture threatening to anyone.
“This gun wallpaper does not show anything that’s violent. It's not showing anybody getting shot in any way. It's just a picture of a gun. It's nothing -- nobody getting shot, nobody getting it pointed at them, it's nothing,” said McClaine. . . .
“To me it's ridiculous. Three days for a picture? It wasn't like he was standing in front of the school holding the gun,” said Daniel McClaine Sr. [Daniel's father] “He should have got a warning. He shouldn't have ever been suspended. Not for something so frivolous.”