However - if that's what they decide to do - then they'll need to leave everyone from the Big10 except for their champion out as well. Because TCU beat the Big10 2nd place team they faced, so if the BIG12 is out due to that, then the BIG10 ought to be out also.
In other words - why would they look at TCU that way but not look at the BIG10 team they beat that way as well?