So if CSAM ends up in an OP_RETURN (of any size) that gets mined into a block, nostr:npub1lh273a4wpkup00stw8dzqjvvrqrfdrv2v3v4t8pynuezlfe5vjnsnaa9nk nostr:npub1lh273a4wpkup00stw8dzqjvvrqrfdrv2v3v4t8pynuezlfe5vjnsnaa9nk will reject that block and encourage others to do so as well; basically a UASF, even when that would effectively mean rolling back the chain.

(Screenshots from the Bitcoin Knots Telegram channel, shared with permission.)