I'm read and saw in documentaries (ones that were actually favorable towards the guy and defending him) many of the girls like Alice's older sister were young teens, because he was hanging around eligible young ladies which were mostly young teens back then (we now see people who marry or go after people that age if they're under 18 as pedos), and the idea was that if the writers made their ages seem even younger that no one would suspect him of being sexual or romantic with the 13-18 year old girls who should be virginal and not associating with men who weren't courting them for marriage or whatever. The girls were already young, but normal age to be married back then.
Nude photos of children were common enough in that era but it was for creepy reasons like them being 'pure' and 'innocent' in an artsy way. Nowadays we see that as weird and gross so he's weird and gross by modern standards. It was also creepy that Alice (and her sister) were his muse, given she was like, super young. And the one photo of Alice people see as being sexual isn't even a full nude, it was one where she is dressed as some specific maid or "character" with the clothes adjusted and posed in a way that was seen as kind of racy then. Nude or partially clothed/disheveled photos of kids weren't just snapping a pic of kids running around or a baby in a bath, they had to sit there posed for extended periods of time for the photo to come out so something like a nipple exposed or whatever in the photo of Alice was intentional and made part of the image on purpose.
There's no definitive proof and all but I also think 20 and 30 year old men who married 13 year olds back in the day would be considered pedos now too even if that was the norm, so I'm not holding him to a different standard than I would hold any other non famous dude.