They thought they were out of the Union. That seems sufficient to me to say that the loyal members could seat whomever they wanted.
Also, Stainless was trying to play fast and loose with the facts. He was in such a big hurry to slam the Congress he forgot that he had in the past stated MOST emphatically that the so-called seceded states were in fact out of the Union.
Walt
It is not inconsistent to say both (1) that courts should have held that states have the legal right to secede, and (2) that, under the law as our courts have decided it, states do not have the right to secede and are not extinguished as entities by an attempt at secession. As a matter of fact, I believe both of those propositions myself.