Because it's not a 303. It a ship based around the Prometheus but a class of it's own. If you compare the shows Prometheus with the Tempest you will see they are different designs but similar in overall style.
If it has the Prometheus on the list someone else must of added the names. The only ships from the show that I have made are the Daedalus and the Ha'tak. The rest of my ships are original designs based on the ships in the show.
No USAF Jumper? haha jk Awesome models though. I stumbled across the Daedalus when I was looking for reference images on it for the 3D model I was going to make. I figured it wouldn't have been done so well already. Obviously I was totally wrong and need to find some other ship to model. haha.
Put any thought into contacting MGM or the directors for the new StarGate: Universe? You've ideas are awesome and if you went about it the right way you could have a job, or at least have your ship ideas used.