Nevertheless there is almost a moral equivocation between images of sex and actual sex by some people. We are talking about restraining someone physically inside a 2 by 3 meter box for multiple years as a retribution for what is after all just pixels on a screen.
(And by the way the implicit comparison here between an image of stalin and an image of a teenage girl is more apt than most would care to admit given the ideological function fulfilled by sexualized images of young women in contemporary American society)