Maybe I am assuming the Vickers are smarter than they actually are, but I think they don't care about the contents on the diary, once your naked daughter's ass being gunted, thumbed and mounted by the Memphis micro is out there. What additional damage could the ramblings of a deranged teenager going public could cause? Maybe the angle is they could use this a way to fuck with Ralph so that he looks bad in future hearings or dealings regarding Xander. If they manage to link him with this diary leaks and cry victim in court (Ongoing harassment, maybe they can argue this somehow is a violation of the restraining order, whateveR) maybe they'll find ways of getting a much sweeter deal when it comes to Xander's custody. Like granting Ralph zero unsupervised visitation rights while getting all of the child support checks from him.