They don't want people to defend themselves. They want to make everyone completely dependent on the will of a government that purposely leaves citizens unprotected and powerless so they can end up easily slaughtered and/or controlled. The 2A is crucially important to preventing that.

On a side note though those criminals look like Meek Mill and Lil B while the kid looks just like Yung Lean. Like the resemblance is uncanny.