Yep, myth. Mr. White is creating a myth that this could not have happened based on personal beliefs and interpretation. As for the part about not being able to hear the ping of the clip, the accounts I have seen were close quarters stuff from the cities and villages in Europe and the ping issue came from the metal both ejecting and bouncing around on the cobblestone concrete/or wood walking surfaces.
As for the second part of the experienced shooter reloading without missing a beat, he is correct in that this could happen ONLY if the shooter was anticipating the clip running out and had a clip handy in the hand. The last round fires, the clip ejects, then the soldier spends a few seconds reaching for one in a pouch or pocket, another couple getting it loaded and the rifle back on target. Watch the battle footage on the History channel. When the cameras remain in place long enough and the program shows enough footage, you will see some reloads taking many seconds. They are not, as claimed, "almost without skipping a beat."
As for whether or not the enemy was that stupid to attack during the brief interval, it definitely could be an opportunity. Better to attack while the enemy is reloading rather than when the enemy is ready and firing.