Ummm.... There is literally already a name for this attack. It is called a reorg attack. Doing a reorg of the blockchain can cause all sorts of problems, and

Ummm.... There is literally already a name for this attack. It is called a reorg attack. Doing a reorg of the blockchain can cause all sorts of problems, and reverse all sorts of things, depending on what those transactions were, and how they are re-ordered.