A furry child in a diaper doesn't necessarily have to be fetishistic, though the artist themselves says it's a kink, so that's obvious intention right there. Sure child(cub)/diaper fetishes are weird, and is a thing in certain parts of furry communities, but there's nothing technically wrong with it.

As far as tracing goes, it's creepy as fuck, I think it also needs to be done in certain means. Obviously if someone traced actual child porn, then that's just proof that they have/use child porn, therefor legal action can be taken. But if someone traced a normal picture of a child then altered it into something sexual or pornographic? While part of me finds that disgusting, the other part thinks we still can't label that as bad under the idea of fictional art being illegalized. I think that would fall under fiction depicting real people in general, right? Which, as far as I'm aware, is always okay. Like when animated and live-action comedies often reference real people to parody them.

Of course the preachiest people almost always have the worst skeletons in their closets.