I don't think the murder or rape of children is acceptable, no.
Do I think it is acceptable that they have had gender reassignment surgery? I suppose ultimately I do. Gender reassignment surgery is a form of healthcare and denial of healthcare is not part of a prisoner's sentence or punishment. If one believes that those experiencing gender dysphoria should undergo gender reassignment surgery before being able to access women's toilets, changing rooms etc and that a grc should only be issued to those individuals that undergo such surgery, surely that surgery must be accessible to those individuals. If one agrees that that should be the case for the general population, then I'm not sure on what grounds such surgery could be denied a member of the prison population, regardless of their crime(s).