I'd say, because this deviation is entirely an original image beyond the pose, that the pose is referenced and not stolen. The way to learn how to draw poses is through referencing photographs and other media. (Think life drawing classes.) It would've been best for ~itori to say, "I referenced this for the pose" (assuming that is true) and to link to it, because that's good sportsmanship. The worst thing Itori can be accused of is a lack of courtesy, and nothing more.
Just to let you know. Every pose has been done before, art isnt new, and there is nothing new in art. Just new representations and renderings. The same goes for music. Everything has been done, there are no new notes. Only new arrangements, and even then... there are over 1000 songs that use the progression C Am F G.
Just to let you know, if you come up with an idea by yourself, it may not be new to the world, and you may not be the first one who thought of it, but it's new to you and you still thought of it, it's an original idea. There's no way that, with billions of people currently walking the earth, never mind the billions of deceased artists over the years, that every idea possible hasn't been covered.
And the comparison to music... "No new notes" is comparable to saying "no new mediums"--what we draw with, which should be fairly obvious. A piece of art is a new "arrangement" of pencil on paper or pixels on screen. Some are similar, but two hands cannot create precisely the same thing, I should hope.
The arrangements are what's important. The tools are irrelevant beyond the final product.
It's a direct copy. Woo. Your argument is invalid.