[dgs_sgd]

This makes it more difficult but not impossible. The EVM has a SELFDESTRUCT opcode [1] that will send ETH at that address to a receiver and it's impossible for the receiver to refuse. A very determined actor could send Tornado ETH to a contract designed to self destruct upon receipt of the ETH and relay it to the intended receiver.

[1] https://consensys.github.io/smart-contract-best-practices/at...

[devit]

You can program your smart contract to forever deny the use of such funds by recording its "non-selfdestruct" balance in the state and only allow to withdraw up to that amount.