It sounds like they're going to be shopping out around to non-Disney buyers, which is a bit of a rarity these days.
It's hard to get a handle on what happened with the BtVS reboot, but one article I read suggested there were (unspecified) concerns with the pilot.

It's always seemed to me that the Firefly cast got the "best" version of Whedon.
Which in no way absolves him of anything he did on other productions - just an observation.