I can understand not citing sources for small things, like borrowing poses or bits. There are often great pieces that use parts of other work and make themselves more original - such as some of bree's (older?) artwork, or Dr.Mc's stuff (which slightly borrows poses). Shoot, I do it, too (for poses mostly). :B You can hardly tell that they're a part of something pre-existing and they look original enough on their own.
But in this case, he definitely should have included that it isn't original: it's a direct copy. o_o