Once upon a time I had the stock off my M1 and the bolt open. I was holding it in my left hand balancing it, sitting in a chair. I leaned down to the right and reached for a brush, the Garand tilted toward the barrel end and the follower touched my thumb, the bolt slammed forward and I had the whole thing hanging off the end of my thumb.
So I'm gonna vote fact
. In the process of handling one with the bolt back, its possible to close the bolt on a finger, or thumb in several different ways. So care and caution should be used. Its probably not gonna cut your thumb off, but it hurts.