Hoss - There would usually be some sort of a messenger on any dead or live but not in use power move. In the NG clime I would imagine that unless the locomotivies had been drained that there was a fire in them to keep up minimal steam to work the lubricator, if nothing else. So the purpose was to protect the locomotive from damage as well as safety. I have experienced all sorts of things happen to modern day diesels when moved DIC. One of the worst was 3 inch flat spots, because someone messed with the way they were set up air wise. Ruined two otherwise perfect historical SD-9's from the SP.
Andy