But if the argument is that it's pretty easy to fly from Salt Lake to Houston, does the same apply to flying from Columbus, OH to Los Angeles mean that USC is a good geographic fit for Ohio St?

Realistically, once we start describing "good geographic fit" as anywhere you can fly Friday afternoon to go to a Saturday game, then that becomes....literally everywhere. Which makes it an odd thing to describe as one of the best things about the Big 12. That it's such a good geographic fit that we can easily fly most places. By that logic, Rutgers would also be a good geographic fit for BYU

Like you said, travel time is travel time, flights change things. Which is why we now have multiple coast to coast conferences. Cal to Miami, Arizona to UCF, USC to Rutgers