Good story, but it was BS.
Carter had already opened the tomb weeks before when they first dug it up. He knew what was in there, or he wouldn’t have sent for his sponsor to come all the way over from England for the “official” opening.
Nope. Carter wired Caernaevon, who had agreed to pay for one more year, and he hustled over and they opened it; however, the official opening was contrived to be a big publicity photo-op type event; they had already entered the tomb, to make sure the event wasn't going to be a big dud. That doesn't mean they went all the way back into the inner shrine -- it took years of careful handling and catalogueing of everything to empty the outer room.