I also have a mean cat and a timid cat, and the mean one, Zibet, terrorizes the timid one, Fipple, whenever she is hungry (which is most of the time) or just feeling like picking a fight. Fipple has gotten pretty good at finding cozy hiding places that Zibet is too fat to find.
I really think that this is happening because Zibet would honestly rather be an only cat... she's very nice to me (mean to my husband, who is mean to her back), and really thrives when she's curled up on my lap with no other cat/dog/human to distract her. We're not planning on getting rid of either cat, since Fipple can find ways to escape when she needs to, but if we did, I think Zibet would be just fine as an only cat.
Do you think your mean cat would be happier as someone's only pet? Maybe you can ask around and find someone who wants one? I don't think you should necessarily assume no one would want him just because he picks on another cat.