Like I stated, the attack did occur but the cub being a cub should have scampered off once it realized that it was not match for its foe. Could be that the cub was orphaned and starving or was rabid which might explain why it didn’t break off the attack. Too many questions and not enough answers to definitively come to a solid conclusion. Only the runner knows the full story and with this being a young cub he’s probably going to stick to the narrative that doesn’t make him look bad. Cheers!
Perhaps the mother had cut the cub loose and it was starving, not having perfected its hunting skills yet. That sounds rather young for a mom puma to cut her babies loose completely. Or, it had an injury which prevented it from getting faster prey like rabbits.
Maybe it didn’t “break off the attack” because this guy had it by the neck.