And, in the middle of a $20 million budget shortfall.
There's more than just COVID testing expenses. There's expenses related to planning your travel to Seattle. You can't just line up all of that stuff and then cancel last minute on Thursday.
Now, maybe the extra thousands in expenses would be worth it to control the narrative. But, it wasn't like BYU had nothing to lose financially by just agreeing to the game.
Also, bowing down and offering to essentially just be a backup plan also gives you a reputation as a lower level team that's willing to do anything to fit in. Not sure BYU wants that either.