Rebellion and secession are different (in theory). According to secession proponents of the day, the Framer's accepted the conditional joining of several states in order to create a stronger union. Recall that the Framers sought to have the union formed of free states, freely entering in to union. If it was compelled, then it was conquest and the Framers didn't want that and no state at that time would have stood for it.

Therefore, the states still being freely joined in union could freely choose to dissolve those bonds.

You are of course, correct that there is no provision for secession. The point was made and driven home with the tip of a saber, not with a compelling legal argument. Sabers win every time.

B