“Supposedly the small snippet selected for dating may have been from a repair that was done about that time.”
Not exactly. From what I recall (and, Swordmaker, please correct me if I’m wrong), the snippet included both part of the original cloth and strands of linen used by nuns in the 1500s or so for a “French weave” to sew up a portion of the cloth that was tearing. Carbon-dating ended up with results for a time period that was in between the time period of the original cloth and that of the Medieval stitching. And I recall reading that some smaller samples that had been taken had yielded widely diverging carbon dates, providing additional evidence that that section of the Shroud did not solely include the original cloth.