How to make curve follow original rotation of mesh? (GIF of problem inside)

I’ve tested basically everything I can and I don’t really know what I would query this problem as on Google. My problem is that I want the curve to keep the original starting rotation which you see in edit mode. I’m trying to make a sort of sheath lock to keep the knife from sliding out, if anyone’s wondering. Any help would be greatly appreciated.

GIF of problem here: https://i.gyazo.com/19cf936ade1e6f5f841f5ba421a78190.mp4