Unless that extinction was not due to human intervention at all, but rather a cataclysmic event causing the Younger Dryas cooling. Maybe the meteor that created the Hiawatha crater on Greenland. [0]
Which doesn't really contradict your theory though, only your reason for the megafauna extinction.
It's a debated issue among paleontologists, IIRC. Surely, human hunting did not help those species anyway. We also know for sure that in more recent times humans hunted many species of large animals to extinction (like giant birds), so until a definitive evidence is provided, to me the hunting hypothesis gets a high prior probability.
It also seems that most mass extinctions were not due to a single factor anyway, but to a combination of factors. So, yeah.
Which doesn't really contradict your theory though, only your reason for the megafauna extinction.
[0] https://www.journals.uchicago.edu/doi/full/10.1086/695704