Pregnant Man Vs Chaz Bono

Beatie tells TMZ ... he reached out to casting in the hopes of landing a spot a few months ago -- but never got a call back. But after DWTS announced that Chaz would be on the show, Thomas says he thinks he knows why he was rejected -- the transgender quota had already been filled.

Thomas says he understands why producers wouldn't cast two famous transgender people on the show -- but he's still pretty bummed out ... telling us, "I wanted to try my new body out. I'm an athlete and I know I would have excelled."