The Catholic Church would be against any armed insurrection which subverted the state authority in the dispensation of justice. The mob was took to itself an authority it did not have to itself. That is what the mob in carthage did do in the end. This said, where there is a proper lack authority, a mob may be most proximate entity to keep order.
However, from a human perspective, when these is a belief that justice will not be served, the people may take matters into their own hands. Given that the JSJ had broken out of jail and escaped in the past, the fact that he had smuggled pistols in the jail cell, should be considered mitigating factors. Being in possession of firearms while in jail just following the rules.
As for the Bible, many crimes required the death penalty. Whether or not a state applies it is and should be left to the prudential judgement of the state. If you do not like the death penalty, that is well and good, but don’t get carried away trying to read into the bible you opinion - it is not there. When it does mean Thou shalt not kill, it means the shedding of innocent blood.