How Does the Immutability of the Cryptographic Ledger Limit the Scope of a 51% Attack?

The immutability of the cryptographic ledger means that while a 51% attacker can reverse their own transactions, they cannot fundamentally alter the protocol rules or the cryptographic signatures that define coin ownership. The ledger's immutability ensures that the total supply, block reward schedule, and the rules for valid transactions remain unchanged.

The attack is limited to creating a temporary, more costly chain reorg for the purpose of a double-spend, not a complete rewrite of the blockchain's foundational rules.