Jim,
He was using the tape to show how reloads could be short, and since the gun closed on a go gauge, but not a no-go, it still had .010" headspace using that round, making it unsafe.
To me, that measurement with the tape doesn't matter, as if the bolt will close on a go, and not on a no-go, then for all intents and purposes, it is safe and to SAMMI spec. If a cartridge were to fail, over being short, then that would put the liability on the cartridge manufacturer, or the reloader, and not the gun, nor the Gunsmith.