Nobammerweed and Hoss covered things pretty well, and also...
There was an interview Brock did hyping what would've been his fight with Dos Santos in spring/summer 2011 where Ariel Helwani asked him about this. I don't remember exactly what he said, but he did mention that he heard from "mutual friends" of Taker talking shyt about him or someone he knew (probably Sable). Brock insisted it wasn't a work he was involved in. Taker had to be working though, otherwise was really calling him out for a fight right there with the entire UFC audience and cameras around, that seems ridiculous.
The idea that Brock was planning on doing some kind of work, then suffered an embarrassing defeat and didn't care about the work after the fight is plausible to me