Quick comic up!
Alright, when I said he communicates through the projector Detta's I mean that's how he usually talks. First of all they let him convey information visually, also they have components that make them much better at deciphering language. When he tries to talk through another type of Detta it takes more effort, so he usually uses the Projector Dettas for conversation. The Moon Elves didn't know he could talk through the regular Dettas, and couldn't take all those out anyway (since they are needed to keep the ship running)
Edit: That particular Detta was heading back to central engineering after having fed the Kilroy.