Fox maybe would have picked up this game, but it wasn't there for them to pick up because ESPN had first dibs and grabbed it and relegated it to the late slot because they needed to fill that and this is "good game" to get in that slot.

Unfortunately, the games are sold in tranches to networks. The Big 12 doesn't decide the time. As noted by others, ideally they'd have a guarantee that by moving these big games to other weeks it is guaranteed those will be in a more prime spot, regardless of which network has first dibs that week.