I don't think it was traced. It doesn't look like it.
Still, the idea of crediting the photographer is interesting. Peveto brought up in that plagiarism thread that he found a source image for a poster of his, and rather than jack it, he contacted the photographer - because it wasn't free use - and bought the rights or whatnot. Could have skipped the process, but didn't. but I assume that was a direct incorporation of the photographic image.
If this photo doesn't fall into fair use, then is the illustrator obligated to at least acknowledge the source photo for their drawing/inspiration?
I don't know either. but it would certainly complicate things.