Oops, I meant the "Bob Ross Company" not the "Steve Ross Company" ... But yeah, they basically own the rights to his name and all of his artwork, and since they own the "Ross" name, his son can't use it for financial gain, from what I understand.
Kind of like what happened with Halston. (If you guys haven't seen the show, I'd recommend giving it a watch. Ewan McGregor being excessively fabulous and having lots of gay orgies.) But yeah, I guess if you sell a company with your name on it, you essentially sell the rights to your own name.