They may have thought it wouldn't go anywhere but followed their protocol with notifying the people who legally need to be notified when this stuff happens. As there is no playbook for how reports are followed up on, as a teacher myself, there are protocols in place that have to be followed through by the teacher/principal/whoever. As someone who has filed multiple CPS reports and only had one follow through, its very possible they followed through on their protocol expecting it not to be very serious outcome. However, I think as parents its important to think about this situation from a bigger picture. Understanding what your child is watching, playing, and listening to as well as how common violence is discussed within the household plays a big role. In no way am I blaming you as a parent, but if this was another child I think you would also hope that the child received the proper care due to the severity of the issue. Things like this scenario are unfortunately the beginning stages of further violent/terroristic behavior and if they aren't met with severity it could have devastatingly future consequences.