I just thought of this... but this situation is kind of like what Captain Ransom had done on the 'Equinox' episodes of Voyager... when he was using nucleogenic lifeforms to fuel his ship to get home... And Janeway didn't want any part of the situation. Granted Voyager is more than a century in the future but The Prime Directive would have existed back then... whether or not it had that many details to it...
It's not killing creatures, but it definitely could have led to that if they continued, I think.
Was nice seeing Pike listed there too.
