I looked into it further, and it looks like bitcoind actually does confiscate some pre-P2SH outputs. For the sake of "simplicity," it applies the p2sh rules to all transactions in all blocks (including pre-P2SH blocks) except ones occurring in one specific block that the devs made a single exception for. Thus, the other exceptional outputs are now unspendable.
Bad news for spammers, looks like The Cat is not setting any precedent when it comes to freezing certain UTXOs. I’d imagine this will result in lots of crying and coping when it makes the rounds on Twitter.
Which UTXOs specifically were confiscated by this? How do I spend to an output that would have been valid before this but is now unspendable due to this change? Otherwise there is no comparison.
A complete list of affected utxos are provided in the stack exchange post I linked to. You would spend them before bybprovoding the preimage to the hash160 hash as the only thing in your redeem script. After the change, you also have to hope the preimage is a valid bitcoin script and then hope you can provide any requisite arguments required by that script to make it return true, and provide those in your redeem script as well.
Thanks for the extra context. Sorry missed the stackexchange link.
