An adult human male with a suitable club is not that far down the food chain when it comes to lethality in the wild.
Predators don’t want to get hurt by their prey and they’ll generally avoid the prospect. Herd animals rarely fight as a pack, and the human tenancy to stand together in a fight also throws off predators.
I think there is a good chance that the cougar would have attempted to convert one of them into a meal if they had run.
I have been told that a adult sized person can fight off a cougar. You will end up with a couple hundred stitches.