Hypersexuality by definition is someone who has extreme sexual urges and desires. I think some psychologists discount that term because it means that it has to be gauged against some scale of normalcy, and sexuality is wide and varied for many people. However, I would think that if someone is driven by their sexual urges to the point that it interferes with the ability to function day to day, then it becomes a problem. For example, feeling the need to have to skip work to have sex, engaging in risky behaviors, etc. Men who are survivors of CSA can have difficulty with their sexuality given that they were sexualized before their time, so to speak, and in an abnormal way. Many resort to acting out later and compulsive sexual encounters can be a result. Does he feel that he has an issue with it? Has he spoken with a therapist about the CSA, and if so, has his current sexual drive been discussed? A good trained therapist could help him through some things if he seems out of control with his sexuality.