Being the former sports director of a small town radio station in SW Iowa, I have a few thoughts on this.
1 - Prep sports are where you make your money. In a lot of towns, high school football is the station's top seller all year long. So when Iowa State (which is fairly hard to sell locally from what I understand) plays on a Friday, it makes things difficult.
2 - If you're part of a network, you should play the games. It's part of the commitment you make when you sign the contract.
At the end of the day, it is a tough decision for the radio folks to make. I'm sure that no station was happy to have to pass on the Iowa State game, but again, for most stations, preps get the nod over college. That's just the way it goes. If your station played a prep game over Iowa State, I'm sure that it isn't a slap in the face towards the university. It was likely a business decision. Just speaking from my experience.