This kind of thing is exactly why I've spent so many times fighting against the left wing. While both major positions in the US are borked, the left wing has an undeserved reputation for being some kind of champion of rights and freedoms, when in reality it's basically in pursuit of a kind of insane facism that denies any kind of common sense. At least with the right wing, even with the bible thumpers, you can see some underlying logic, especially when you consider the origins of the country. Things like this though are just insane, and honestly I kind of saw it coming a long ways off, but nobody really wanted to listen.
The basic story behind this comes down to the simple fact that the left wing holds a very solid "we believe in free speech, as long as it's the free speech to say what we agree with", in the name of "freedom" it's also been trying to shut down avenues of resistance against the authorities and the abillity to speak against social trends they support (hate speech, which can apply to so many things it's insane), and of course dedicated efforts to try and prevent the same kinds of civil disobedience and efforts that acted as a springboard for the left in the 1960s and 70s from being used against them.
When it comes to specifics, what happened was this little thing called the "Columbine Massacre" which while not the only school shooting in history, happens to be the most famous. Like most tradgedies, rather than the actual causes being examined, and the system properly reformed, it became a springboard for politics. The basic agenda the left wing pushed through was to pretty much try and ban all violence and violent expression from school, and demonize the bearing of arms (guns or otherwise) which has been a long standing position from the left. Passing these school policies lets them get the kids while they are young.
Over the years we've watched these policies go from people talking about violence in school, to talking about violence at all, to drawing pictures of weapons, to even wearing T-shirts and such which might have violent material on them. A movie T-shirt for "Clash Of The Titans"? Go home immediatly, the guy is holding a sword!. Over the years I've read a lot of things about this, and truthfully the violence ban has probably done more to keep people from reading comics (violent) on their lunch breaks than the arguement that comics were bad for kids to read ever did. I even remember a case a couple years back where a high schooler was expelled for reading Harry Potter (with one of those concealable book covers), due to violent content, and having the audacity to oppose this stupidity (I don't remember if it was overturned or not).
At any rate, trying to ban deaf kids from making "violent" signs under any circumstances is pretty much par for the course, and really it's because we've let things get this far politically. The kid's name is "Hunter" which implies you know hunting things (which traditionally means killing them) so it's not surprising the name involves an aggressive seeming hand sign... the next step is probably going to be to effectively ban kids from being named things like that, or forcing them to adopt a "school name" if their name is too inherantly aggressive. Give it another couple of years without some opposition to this, and we'll probably have politicians with books of baby names turning "what does your name mean?" from a fun fact to a way of making your life miserable. "Your name is Cassandra? That means Prophet Of Doom, change it or you can't go to school, if you won't go to school your parents go to jail...."
My extreme sentiments on certain subjects aside, I tend to stay in the political middle, swinging a bit towards the right, for a reason, it stays away from this kind of insanity. The Right wing taken to it's extreme is just as bad, but right now it's been the rise of the left that we're dealing with. This kind of crap is pretty much the left wing anti-gun equivilent of an insane right winger trying to pass religious policies, it's just people are blind to the left wing right now and the needs for balance.