Who said the Constitution had to be signed by all?
From the beginning, it was agreed that only nine states had to ratify the proposed constitution for it to be established.
Actually, there is no reason why non-slave states couldn't have formed their own nation if they had felt strongly about it. But, they didn't feel strongly about it because it was not in their economic and political best self interest to feel strongly about it.
And so the original 13 slave states voted unanimously to include slavery in the United States Constitution.
Do you believe the original 13 slave states had corrupt motives in forming the new nation?
The Articles of Confederation and Perpetual Union made up our first “constitution” (Note that the Southern states signed a document stating they were are permanent part of a “perpetual union,” as that again proves the lie to being able to abandon the Union.).
Having the Constitution only formally owned by nine of the 13 colonies would not have been a ringing endorsement of the Union. Sure, it would have been legally bound by all states, but it would be less than optimal for a long term future. Strangely, it’s not unlike Congress and bills that pass by the minimum needed—it may be flipped back the other way by a future vote.
The idea the states could firm a separate nation when they had signed their oath to a Perpetual Union already, is ridiculous, on its face.