Public protection is not the only reason for jailing individuals, although who's to know whether Glitter no longer presents a danger to young children in some perverted way; there are also the elements of rehabilitation, deterrence and punishment to consider. Glitter reoffended when released and looks past rehabilitation. Unfortunately, there are others like him at large and imo a strong deterrent message needs to be sent. Wrt punishment, I find it difficult to have much sympathy for Glitter and to use the old saying, 'He's got what he deserved'. I agree with @Effective altruism ; he should spend the rest of his days in a cell.