Read the quote. The context is clearly talking about civil authority
If by civil authority, you mean governments, police, military, etc., then, no, it is not. Well, maybe in Europe, but in the States:
those who legimately hold authority
In the US, this refers to every citizen. Every citizen has legitimate authority. Note that is uniquely an American perspective, and much of the world doesn’t understand this distinct point of view of America’s Founding - that it wasn’t a collectivist movement (like the French or Red Revolutions), but rather a collection of individuals desiring individual freedom, and thereby, meaning that individual citizens have authority, legitimately. Every citizen has the right and responsibility to use arms to repel aggressors against their civil community.
In the Constitution, it’s referred to as the “militia”. Some like to think the State’s national guard is the successor of the militia, and that’s partially true - in the sense of the cases of state-wide sponsored organized militias. However, the militia didn’t refer to an institution of the various States, but to the citizens willing to defend their States. The militia were the citizens willing to take upon these responsibilities when called upon.
Now, much of the world doesn’t follow this. In fact, much of the world doesn’t understand this. That individuals were endowed by their Creator by unalienable rights. It’s self-evident. Well, it wasn’t - not back then. Back then, it was self-evident that God endowed Kings and Queens with unlimited power, not that all men are created equal. It’s arguable, by the posts here, whether all men are equal, or if only the anti-gun people are equal.
I say this as a Catholic who wears my concealed handgun wherever I go, including Mass.