While I do kinda understand where Metal's coming from; I have to say I don't see anything "sexual" about this picture at all. Really finding, sexy,cute or anything else is in the eye of the beholder.
Also another way of looking at this is that Aloysius is simply imaging what Ms. Black might look like when she gets older.
I personaly think she looks very cute and that's it, to me the things I take more from it are the same things that I take from most of Aloysius artwork, the incredible skill the way that his subject's faces are spot on the little details in the clothing and the folds both on the clothes and the flesh.
i never trust wiki because anyone could put stuff on there so u never know sure she could be 15 but that might be someone opinion based off of their opinion on her appearance. u'll never know unless u have a more reliable source.