Apparently the administrations of the two schools (Texas A&M and Texas) are sensitive to the fact that this is a traditional rivalry that has been on hiatus and they see it could return in the future but they don’t want some lower-tier bowl (even if its in their home state) to gain the windfall of resumption of this rivalry, especially under the circumstances of each team having a disappointing season (even though Texas hasn’t qualified for a bowl since 2014 – shows the arrogance of the Wronghorns right there).
Some of this is buried in the middle of this long “mailbag” article in the Austin Statesman
https://www.hookem.com/football-news/football/whys-texas-super-sized-mailbag-takes-us-6-6-roller-coaster-emotions