Pretty sure the Big Ten/ACC/PAC 12 don’t care who gets the playoff, they just wanted it to be open for bid. The reason ESPN tried to force playoff expansion is they have exclusive negotiating rights until their CFB Playoff deal expires in 2025 and any contract signed before that would have extended those rights. The other conferences just want to get to 2025 so that they can have a real bidding process and everyone can bid, maximizing the return they get.
I’m pretty sure they want to model the CFB Playoff like the Big Ten Championship, passing around the games between networks, to not be locked into one network and to get two (two networks each get one semi-final game and the championship rotates) or three network (three networks each broadcast one playoff game on a rotating schedule) bids, like the NFL does with their playoff rights.