Hardly. It was the reason for their rebellion. Just ask Alexander Stephens, among others.
So I am constantly told by people who attempted to justify all the bloodshed and upheaval for doing what they did.
Works on silly people of mediocre intelligence, but not so much for anyone else.
Again, "Corwin Amendment". Hello? Hello?
You can't very well pass an amendment that guarantees slavery forever, then come along and pretend you needed to fight a war to get rid of slavery.
The one thing you can tell from such history is that the reason for the war was clearly not slavery, because that was attempted to be handed out on a silver platter, but was ignored.