As seanwilson says above, blockchains work by consensus. Leaving aside the "better", that does mean it is different. The instructions are still executed by computers as it was programmed as you say, but if enough users/miners agree this was not the intention of the contract/code, they can fork.

I do think that calling blockchains "immutable" can be confusing to users not familiar with the concept and its nuances. And I personally hold no opinion on whether the currently locked up funds need to be returned to their owner with a fork. There is something to be said for both options, specifically in this case where there the "rightful owner" is clear (like the other cases mentioned in https://github.com/ethereum/EIPs/issues/156 ).