Prolonged denial of sexual activity is cruel and unusual punishment (torture) for any sexually active adult primate. Furthermore, sexual activity makes primates less prone to violence. If nothing else for the safety of the guards orgasms should be allowed and encouraged.
If the criminals turn violent without sexual activity, then they should be castrated, or treated with drugs which can reduce the testosterone levels. These people are imprisoned for committing heinous crimes such as rapes, murders and armed robbery. They can't demand that the prison authorities should bring them sex-workers to satisfy their lust.