Other articles about this incident have included skeptical comments from Dept of Fish & Game wardens. It's easy to see why -- the guy is standing, wearing a backpack suitable for a day hike, when a mountain lion jumped on the backpack and hung onto it. The guy gets knocked to his knees and hits the cat with a backwards swing of his rock pick, but the cat doesn't let go of the backpack. (Just picture the scene.) He's a 69-year-old man on a steep incline on his knees with a mountain lion clinging to his backpack. He raises his rock pick for another swing at the mountain lion behind him on his backpack. That's when the bear gets involved. And he ends up with some bruises and scratches.
Uh-huh.