I also thought it was interesting that he mentions that at the time, that they had heard rumors that that had worked. He called them tricks. I agree there's no way you could hear that in a huge gunfight, but I guess in certain situations you could
I suppose it might work in a one on one situation or with one soldier guarding a staircase. The enemy would have to think that they were facing one opponent for them to rush his position after a ping.