CU will get $2 million for playing at Ohio State if it happens. That's double what CU makes at Invesco. According to your reasoning, CU can't afford not to play games like that. Perhaps CU should replace the CSU game with one shot away deals at big stadiums. Don't kid yourself, those programs are dying to get home games against beatable BCS conference teams, especially if they don't have to travel to Boulder in exchange.
The fact of the matter is that CU, by being locked into the CSU game every year, loses some opportunities. This will be even more bothersome if there are 9 conference games in the PAC 12, leaving only 3 non-conference games. Every game against CSU means one less chance to play in the Eastern or Central time zones (games I could attend), every game where CSU is the home team will be on the mtn. and unseen nationally. None of that is worth the $$, especially when opportunities exist to make more money and gain more recognition by playing at a top 20 program.