Of course this is BS too. Read Red Earth, White Lies: Native Americans and the Myth of Scientific Fact by Vine Delora.
Br'r Delora has a different agenda than science.
The fact he wants to lift the blame from Indians for wiping out the megafauna means he hasn't got a good grasp on the situation.
Fact is the Younger Dryas probably killed the megafauna. First the ice melted and vast grasslands filled in South of the melt. The megafauna moved North to eat the new grass and escape the encroaching forest lands. The big cats went with them.
Then, one day, the Younger Dryas happened in a flash, and the ice age conditions came back instantly.
The megafauna could not flee South fast enough and they and the cats that lived on them ALL FROZE TO DEATH if they didn't simply starve.
The greater part of the ancestry of the American Indians came here only 5,000 years ago ~ the megafauna had been dead for 6,000 years by then!
That's why the Indians aren't guilty.