There's a lot we don't know yet that may become more apparent by the final candidate chosen. It certainly may be a case of either or both sides not wanting to pursue the relationship. Removing their names could be a way of saving face as Blueline Bomber mentioned. Both candidates that have confirmed not being in the process anymore have been in their organizations a long time and may be very set in certain ways. Perhaps Dundon's proposed structure isn't crazy, but just far enough outside the norm of what these two have dealt with in their lengthy tenures with other teams. Maybe they haven't meshed with Dundon on a personal level like Francis didn't.
Of course, it could be any of the negative things that have been speculated with meddling owner, money issues, reduced role, whatever. We'll see who we end up with. I'm sure there will be some rumblings after the fact.