It's a threat of violence, not actually conducting violence. Maybe I'm just using the wrong word here. What I'm trying to say is more than a decade in prison for threats where no one got hurt seems excessive.
Yeah our court system is broken, but due to it mostly happening to minorities, no one balks at 15 years for having a joint when you're brown. No congressmen are called, no revolts of society. Just "well, they deserve it." But people don't realize it sets the tone for sentencing for all tax paying citizens.
This is what happens when American society allows excessive. If you can't afford good representation, or you catch a judge on a bad day, your life is over.
In that world, you should know better than to make people fear for their lives, including children. If you know people are in jail for much longer for less. They thought they wouldn't catch a long time. Because generally, people that look like them dont.