From what I read one of the main drivers for "Lets let in Stanford and Cal" was Notre Dame, to which some ADs more or less told them that they should STFU until they come and decide to be a full conference member.
And it is likely that any push by Notre Dame in this regard was likely to make sure that the PAC-12 was killed and gone and thus losing their auto-bid to the playoff, making it easier for the Irish to make it.