It is nit-picky, for certain, but RAW IMO. Personally, I would not be this crazy about not allowing the spell to provide space for a secure Short Rest, but for people who don't want that functionality, here you go...
Since the rule for a Short Rest is "at least one hour", the spell wouldn't allow enough time by itself. After all, each character would have to take time to climb the rope, so with that time spent, they would not have an hour inside the space provided by the spell. Since a character can't do anything "more strenuous than eating, drinking, reading, and tending to wounds", after the spell is about to expire and everyone climbs back down, that would be "more strenuous", thus reseting the clock on the short rest hour.