Yeah, it is a flap of skin, and it does seem to be dying. I'd take more pics, but the only camera I have is a cheap one that I got second hand years ago, so I wouldn't be able to get a better pic anyway.
The scales seem to be coming off of the rest of his body, just the top layer, which I think is a sign of dehydration? (looked for hours, and I only found vague reference to this being a sign of dehydration) He IS drinking, though, and I've seen him in his water several times, so I suspect that he's getting the polysporin on his other scales, and it's keeping water from getting to them.
I bathed him yesterday so that he could soak up water (let him go through a wet towel to get the polysporin off his body) and so I could carefully inspect him. He doesn't have any discolored spots and he digested his last meal just fine (second feeding since the incident) so I'm pretty sure he's alright internally. There is a slightly hard, off-white-ish colored layer over the majority of the wound that I'm assuming is a scab, since there is absolutely no inflamation or discharge, so I was thinking of discontinuing use of the polysporin for a short time to monitor the condition of his scales.