Regarding the original story:

If this guy had made some noise and carried pepper spray, this would have been a happier story. But in fairness, there are some areas and trails where you don't expect to encounter a mama bear and cubs.

He was ridiculously lucky. Lucky to find a club of suitable size and strength in the midst of the fight, lucky to stun the bear with a hit.

It may seem harsh to destroy the cubs, but I doubt they would survive the winter on their own. So the other option is slow death by starvation and exposure. The wildlife officer on the ground is generally better informed than anyone else to make that call.