I'm guessing Ubisoft is expecting Tour Mode to get used as an educational tool, which would easily explain this. Otherwise, this does sound disappointing though.
That seems to be the case. But in a way that makes it even worse, means that ESRB/PEGI/etc. won't give it a Teen/12 rating with the nude statues still in. How is nude art so bad that it would raise the rating of the game from Teen/12 to Mature/17? We might need to rethink our rating guidelines, nude art is perfectly acceptable in an educational game imo. It's not like kids won't have already been exposed to it at some point, if they've ever gone to an art museum. Heck, there's an Italian restaurant in my town with 2 nude female statues at the entrance, lol.