It has copy on its site stating it "allows multiple different parties to securely interact with the same universal source of truth."
I think the fact that IBM is running this, and not Walmart, is actually a plus. The suppliers don't have to worry about Walmart itself making data changes. Of course the details will vary, but I highly doubt the platform allows the account owner to unilaterally make changes to this source of truth. It's totally against the point of the project.