There is no law that prevents 51% of the node operators from forking the Bitcoin code. Even if there was, scarcity isn't the same thing as value. My kids art work is incredibly scarce compared to Bitcoin. I can copyright it so that no one can copy the only original that I own. But that doesn't mean it is going to go up in value.
You are not informed. Forking is not the issue. There have been forks before. Rewriting the chain history (which is extremely difficult by the way) is the issue.
