I wouldn't say that the CU players and coaches treat the game like a rivalry game.
Since McIntyre took over they take it seriously as they should. CSU is a team that if CU doesn't take them seriously can beat CU and since they are always up for the game given that opportunity will beat CU.
There is a big difference in the importance of the game though. CSU, good season or bad in their other games, fans care a great deal about winning the CU game. It makes or breaks their season, it is the game they remember. The players, coaches, and AD knows this. Beat CU and they have more fans in the seats the rest of the season. Win or lose against Wyoming or Air Force or Boise they go first to the CU game.
For CU losing to CSU is a bad look. They need the win if they want to be in a bowl game or in a better bowl game. Unless they lose and it hurts them though it isn't the game fans, coaches, and players focus on.
In our 10 win season a couple years ago was the CSU game a key game? When that season is discussed nobody talks about CSU, they talk about beating Oregon, beating Stanford, and what could have been had we beat USC. Those are the games that matter enough to be the focus of a season .