Hypothetically, there’s no immediate option to escape a person who has attacked you and is intent on causing you further harm. Do you think you would be able to fight back and create an opportunity to escape? Do you have a plan for if things go sideways and you end up on the ground with them raining blows down upon you? Can you fight to survive until your last breath?
Adrenaline goes both ways and it’s wishful thinking to believe it will save you in a fight. It will make little difference against a trained opponent. Even the guy in the story admitted he got lucky. The young mountain lion cut his throat and could have easily hit an artery. He was only able to kill it because it bit into his wrist and was too stubborn to let go.