In that scenario, it isn't clear which of these is correct.
A. No head to head, go to next highest common opponent (ISU), Texas and OU have wins, OSU has a loss, therefore Texas and OU in to the championship with OU the #1 seed due to head to head.
B. No head to head, go to next highest common opponent (ISU), Texas and OU have wins, OSU has a loss, then to break Texas and OU use head to head, which makes OU #1 seed, then restart the tiebreaker between Texas and OSU, go to highest common opponent (OU), OSU has a win, Texas a loss, therefore OSU is #2 seed.
Scenario B is what Alex Loeb has stated, and it isn't clear whether he got that from the Big 12 or is just assuming. Scenario A makes a lot more sense.
Edit: There is a Scenario C (bolded is what is different from Scenario B)
C. No head to head, go to next highest common opponent (ISU), Texas and OU have wins, OSU has a loss, then to break Texas and OU use head to head, which makes OU #1 seed, then restart the tiebreaker between Texas and OSU, go to NEXT highest common opponent (Kansas), OSU has a loss, Texas a win, therefore Texas is #2 seed.