At least in my state, this is considered sexual abuse of a minor.

It's not considered anything actually, because it's not real. This a fictional comic and for that matter, ouija boards don't actually let you talk to dead people...

I mean, having "dark" twists is pretty normal for this comic, what gave you the impression it was intended to be wholesome?

This is extenuating circumstances, it was unfinished business! Who knows when he'd get another chance.

The magazine titles suggest nudes only, not full on sex scenes. Learning about what bodies look like can be a healthy part of childhood.