Reasons for sedition and insurrection are irrelevant to the crime. Shooting a high school student to stop him from shooting other high school students (if you're not the police) legally is murder and must be charged as such. Hopefully, acquitted. The concept of justifiable homicide in criminal law is a defense to culpable homicide (criminal or negligent homicide). Generally, there is a burden of production of exculpatory evidence in the legal defense of justification.

The early U.S. government was, in my opinion, right to revolt. Yet, there it is: sedition and insurrection.