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No, Bitcoin transactions are irreversable. If an exchange was to unwind a commodity trade they could only change ownership of the contracts or physical goods that are deposited but not the money. Thus they can't reverse both side of a trade - reversing only one side would be theft.
not in the setting of a custodial exchange where the transaction does not settle to the blockchain but stays in the exchange's ledger. highly unlikely in physical commodity exchange that people will be using blockchain settlement while awaiting physical delivery of the nickel