Certainly, it "rigidly" enumerates powers:
It was in fact neither one, but because this power could not be used if it was called what it really was, the order went out to continuously call it an "insurrection" or a "rebellion."
Rebellion is a master/slave relationship. It does not apply to members of equal status. It does not apply to states leaving an organization of which they no longer wished to be a part, and doing so in a democratic and orderly fashion.
But Lincoln could do nothing about it unless he could put forth some sort of figleaf to justify the power he would have to claim to stop them.
Beyond that, Article IV, Section 2 still says slaves have to be returned so long as they are held by the laws of any state.
It specifically says no state law can prevent this, and because it is in the main body of the US Constitution, no congressional law or executive action can override it either.