This seems like the opposite of true to me; if they intend to mutate the records doesn't it become extremely helpful that the records are immutable? What am I missing?
That said, the same thing can be accomplished by outsourcing the public ledger to a third party with a reputation for trustworthiness. The same way that countries that cannot make a credible commitment to not devalue their money will often peg their currency to the dollar or the euro.
Which is where trusted counterparties like the one you suggested are a much better bet than an untrustworthy party enforcing and administering a record and its exception handling, even if that record itself is immutable.