he said he made that in 13 minutes. He doesn't need to prove his skill to you.
Calling someone a thief and demanding some kind of proof of their skill (of any level) doesn't make you look better as an artist or a member, in fact it diminishes your image imo.

He put up his sources, he knows he pieced together a hat of existing work and minor adjustments, dunno what else you want or why youre attacking him.