I can understand why external storage would be frowned upon. I've seen posts here on this site where external storage is used as "out of sight, out of mind" which isn't great, and depending on the area around your store it could be a real eyesore, or take up too much parking lot space, or be a target for theft, etc.
That said, if a store has a place for external storage and has a history of using it appropriately, there should be exceptions granted, or Spot needs to offer alternatives if the space inside the building doesn't meet store needs.
And if it takes OSHA complaints to get there, well, then so be it.