Your imagined scenario is missing a piece of information: Texas Tech, also 11-1, is the team that beat Texas.
In a two-way tie, head-to-head should rule. Obviously. In a three-way tie where the teams went rock-paper-scissors on each other, head-to-head can't rule by itself because it doesn't determine anything. And I don't see why it's any more legitimate to throw out one team and go back to head-to-head than it is to compare all three on the same scale and pick the top from that alone. That's not to say there isn't a case for Texas - I think there is if you factor in the increased degree of difficulty in having the OU-Mizzou-OkSt-TTU gauntlet all in a row. But there is a reasonable case for Oklahoma (which really wouldn't be there if Tech wasn't involved in the tie, because of head-to-head).