I think the hairs are also how Rumpel knew that Snow and James’ child was the savior on her 28 birthday. Because the hairs together are true love and Emma was made because of true love, so he knew that Emma would be the savior. And wouldn’t the curse then be specificly for Snow and James? Because Rumpel said that “no two loves are every alike” so he took Snow’s hair to make it more personal. Or did he only do that so he could get her hair?