It is not uncommon to see furled headsails come unraveled, I've seen it happen in quick thunderstorms but a furled mainsail?
Rather than being "rough", I think it's important to get the whole story which can serve to benefit everyone here who has a furling main. Don't know why this is still a mystery.It's a rough room, here!!! ;^)))
An in the mast furling main might be a different case. At a dock in a reasonably positioned marina is probably in pretty good shape -- as long as the rest to the boat is pretty cleaned-up. In this case, Ron's discussion was related to ONLY the main. If his lines let go, he wouldn't be talking about some old Dacron :^))).
Why if opened-up is a different story. I don't have an answer for that.
I gusseted our main in Massachusetts after removing all the canvas, headsail, ourselves to North Dartmouth. The boat was on the dry in South Dartmouth during the last (almost) hurricane a four or five Augusts ago.