When the model and parents are willing, as in this case, it may remove worries of direct exploitation but that does nothing to reduce the creepiness of seeing a kid posed in a sexy way for an anonymous audience. Why is that? Who is harmed? I'd say that beyond the degradation of any individual, or even providing an unhealthy opportunity for perverts, the travesty is in the effect on the culture at large. When kids are imaged as adults for adult pleasure (and especially for profit!!) all involved are subtly nudged away from seeing the model as a real person. This is even the case with a willing adult model. They may be privately assured of the falsity of their own degradation and thus safe from it, but the rest of society suffers from a general deflation of the human spirit as the complexity of the real person is reduced to a one-dimensional clone of the fashion icon.
This is what much of my work of recent years has been about, especially with the Body Psalms films. In that project I try to counter this degradation not by negating sexuality as the church as done for centuries– to infamously disastrous results– but by reminding the viewer that what is unnatural is not sexual interest but the reduction of a person to an object: OK for mythic figures, but not OK for real human beings!