How many accusatory calls does an athletic department deal with daily that we never hear about, not because of cover-up, because the accusations had no basis? Many. The job of professional assistants are to filter what is actionable from all the noise. If this whole thing makes CU look oily, it only does so because we have all the knowledge in hindsight. Imagine getting a call like that from someone you barely met once, accusing someone you have known professionally for two years...all while preparing for a bowl game with a short-handed staff and trying to finish up recruiting. If there is a victim who is it going to turn out to be: the caller, the assistant coach, very possibly yourself. Hard to say. You have two seconds to decide what to do. Since the caller is safe, you decide to wait and see if more data emerges. It quickly does and then you make your decisions promptly based on that data.
If you see the admins perspective, while they were in the moment, I think you have to admit they did an admirable job. Though the whole thing is sad, I don't even think 'mistakes' were really made.