Is there any chance Brock and WWE have already come to terms on a new contract, and the "walk out" was just a work to make people even more unsure of the outcome of Mania (keeping in mind most assume Reigns is winning anyway, but you know, b/c WWE)? The fact that Brock was sitting ringside at UFC 184 may just be a happy coincidence.
Yeah, but nobody knew about the walkout and to date we still don't even know why he left or what happened. All we know is some vague info about him getting into a fight over financial matters with Vince and then leaving. Not to mention that if Vince gave a shit about what the internet thought, Daniel Bryan wouldn't be the 17th guy in a midcard Intercontinental title match at Wrestlemania.
I think it's far more likely that Brock is playing some supreme contract hardball and either WWE or UFC is gonna pay a shitload of money because of it. All Hail Brock.