I don't think you can "debunk" something merely with strong evidence.
Besides that, I wasn't aware of this codex, so I'm glad you shared it. Has anyone suggested that (assuming there is a relationship) the arrow of causality might go the other way? That perhaps this image was a reference for the shroud itself?
The C14 dating is one evidence, and there are plenty of contradicting evidence for the 14th century dating. But my main point is that there is at least doubt for the 14th date, and any proper scientific approach should at least mention the codex.
Besides that, I wasn't aware of this codex, so I'm glad you shared it. Has anyone suggested that (assuming there is a relationship) the arrow of causality might go the other way? That perhaps this image was a reference for the shroud itself?