Technically, it’s not Bitcoin if I can’t run Satoshi’s code and sync to the new chain. You can claim all of the historical bits and the UTXO set up to the height of the fork, but logically you are no longer conserving the same work. If the proof-of-work algorithm changes, the function and difficulty will have been altered by fiat (decree). This becomes obvious when you calculate the block energy of the chain in joules. At the fork, the thermodynamic history will deviate because the system is no longer conserving the same proof of work against the invariant Satoshi defined at Genesis. The POW change will alter the Boltzmann entropy but keep the Shannon entropy via the utxo set. You can point back to Satoshi’s Genesis and call it Bitcoin, but ancestry is not identity here. The proof is in the computation of the work. Follow the joules through the fork and you will see exactly where conservation ends and fiat begins. You don’t need to trust me, you can verify this for yourself. “All things are lawful for me, but all things are not expedient.” — 1 Corinthians 10:23