Nodes can't effectively implement something like a sanction list with relay policy alone.

As soon as a miner includes a transaction in a block, relays have no choice but to add it to the chain. I suppose they can refuse to relay all block data and purely listen, but they can't selectively relay valid blocks unless they have very high certainty miners won't build on those valid blocks they dislike. If even a small percentage of nodes are relaying the valid blocks, miners will quickly learn about them.

As for implementation of such a sanction list via policy around unconfirmed transactions, they would need to have something like 95% of the nodes on the network agreeing with them and be certain no miner learns about the transactions they don't like via any other means (eg transaction accelerator services)

See @murch's answer to my question in this thread: #348402

Nodes enforce consensus through what they will accept as consensus valid, not through their policies about what transactions they will relay.