Yes, the Silent Ones would be a great fit for Argent. In the Revenge of the Giants adventure, there is only one guardian (called Silver Cloaks) left in argent - Obanar. He can easily be a Silent One. One of the primary missions in the adventure is to recover pieces of the divine engine. The pieces have been stolen and scattered and the Obanar wants them back, because the divine engine is a powerful artifact used to bind primordials. Seems like a perfect fit for a Slient One archetype.