I can't speak for Walt, but from what I see there was no selectivity to it. The southern states were never out of the Union.
Do you want me to start pinging you when it shows up?
Here we have another obvious Lincolnian paradox. He was authorized to implement a blockade under the rules of international law. Any action involving a state of the Union would have required Constitutional approval. The SC did not cite the constitution. They cited international law. Then they play a game of switching back and forth between the two, using whichever is to the union's advantage throughout the war and reconstruction.
As a resident smary guy, I assumed that you knew and appreciated this, but just accepted that their right to do so needn't be questioned because their dicta carries with it the weight of law and the wrath of Lincon's enforcement policies (i.e. wielding power is the government's responsibility, justice be damned).