Because of his own personal choice. Not mandated by the captain.
It is a strange design but it doesn't strike me as any stranger than past ship designs.
"The Good Shephard."
The way they went about hand delivering a request to the "plasma relay room", it would seem somebody would be assigned there.
It was clearly a silly plot device meant to introduce us to one of the misfits in the episode. Like they couldn't reroute power from say, engineering.