Taking just ASU and UofA sufficiently weakens the PAC without having to add even more schools of little value.
If the B1G doesn't accept OR and UW, than the Big 12 will accept them with open arms. Both have built good brands that would add good value to the Big 12.
There's no need to significantly value the Big 12 simply to finish off the PAC when they are already on life support and have been proclaimed brain dead.