Belz...
Fiend God
I've seen this analytical fallacy multiple times -- you are assuming a priori that the Shroud must have been tightly wrapped around the corpse, rather than loosely -- except that the image on the Shroud belies this assumption. ergo the assumption is wrong.
It's been explained to you already that it doesn't need to be tightly wrapped.
I don't know why, but I see a pattern emerging.