Hi
He is right on the statement that WLC does not rely on Monitor AP to take decision.
Monitor AP is important for wIPS cause it monitor all the channel thus increasing security.
Also for troubleshooting. You can install Cisco Spectrum Expert, which is free, point it to the AP and you can analyze the spectrum surrounding the AP.
It is useful for interference problem.
-If I helped you somehow, please, rate it as useful.-