We don’t need 5.56mm tumbling rounds to stay safe.
As Carl, th4, and Delmar have pointed out indirectly, this dude(tte) is throwing out buzz-words and -phrases (s)he's heard, but doesn't understand. If a bullet tumbles in flight and the range isn't short, there's a term for that, "a miss"! The rifling in the barrel of a ... rifle ... causes the bullet to spin,
preventing in-flight tumbling. OTOH, every bullet tumbles within the target - human or animal. It's due to physics, the high velocity of the round, not intentional design. The purpose of high velocity is accuracy and longer range (angka probably didn't even take high school Physics, so I won't elaborate).
I knew the purpose of rifling when I was in 5th Grade, not because I or any of my family were "gun nuts", but because I paid attention in American History, when the difference between a rifle and a musket was explained.