Either the Union was voluntary or it wasn’t.
(Yes, I know this elevates states to the same level of analysis as individual actors.)
So what? States should have every right to voluntarily secede from the union. I can’t wait until the certain state I live in is able to.
States have rights?
Don’t be too harsh, I guess F4M meant “rights of individuals to voluntary organize into independent groups of any size, however small, should be widely recognized”. I will leave it to him to clarify, though 
I’m all about secession. If states are allowed to secede they will be less tyrannical. I support every kind of secession there is. Individuals should not be dominated by anything or anyone.