It's interesting that Apple does already sell music with explicit lyrics and R rated movies as well as television content like Game of Thrones and video games with violent content (all labeled with appropriate ratings so parents can use the provided parental controls to exclude them on children's devices).

One wonders why it wouldn't be good enough to give explicit apps an accurate rating and go on about your business, given what they already sell.

My guess is that this case was more about being wary of what sort of content they produce in house than what they sell.