It is immoral to do something contrary to the constitution. That's not a debatable point, as I see it.
How is that not debatable?
It is a theory of government, not an ethical theory. It is not immoral to have a different form of government, or even break a trivial component of the constitution. For example:
"Each House may determine the Rules of its Proceedings, punish its Members for disorderly Behavior, and, with the Concurrence of two-thirds, expel a Member."
If a government required 5/8ths instead of 2/3rds, would that government be immoral? Or is it just US citizens that obligated to follow every point of the Constitution?