
The proposal seems to be: * If a transaction contains illegal content, rather than relaying the transaction content, relay a ZKP which proves the transaction was valid without revealing the content of the transaction. * This is TECHNICALLY a hard fork, because without the actual content of the transaction, the block shouldn't be considered valid. The definition of valid is expanded to include transactions for which a ZKP is provided. * This doesn't necesarrily cause a split in the network. Nodes using the ZKP would see blocks from nodes NOT using the ZKP as valid. But nodes NOT using the ZKP might consider blocks not containing the original transaction. But presumably they could get the original transaction from another node. * There is a censorship risk, since the ZKP only proves the transaction was valid, not that it actually contained illegal content. So if nodes running NOTS recieved a directive to replace a particular transaction with a ZKP, they would stop relaying it. * Presumably it would only apply to OP_RETURN transactions.