couldn't kill him, not sure how harald would. harald would also be unable to ever touch borg who could blast away with heat vision basically forever. and probably do nothing with it....
they'd mix it up h2h but borg would know he couldn't win that way so, not sure how this wouldn't be an eternal stalemate.
That blast definitely rendered Henshaw inert/incapacitated, as it wasn't until the Manhunters intervened that his life readings registered 'positive' again--prior to that, they were 'negative'(as we see in your 3rd scan)... But that was also a galaxy-busting explosion, which Harald obviously cannot generate.
I'd agree with the stalemate route as well.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."