Someone can setup "watchdog" services that you can give your revocation transactions to and they can watch the blockchain for any attempts to "steal" your money and if any are found they can instantly broadcast the revocation.
Doing it this way you don't give the "watchdog" service any control of your BTC, just the ability to broadcast countersignatures, which means there is still no counterparty risk here. You could even give your revocation transactions to multiple 3rd parties that can all watch the blockchain for you if you don't trust any one of them to not backstab you.
Doing it this way you don't give the "watchdog" service any control of your BTC, just the ability to broadcast countersignatures, which means there is still no counterparty risk here. You could even give your revocation transactions to multiple 3rd parties that can all watch the blockchain for you if you don't trust any one of them to not backstab you.