No less a personage than Ansel Adams used reality as a starting point, and would come back to his favorite negatives over the years -- which he called equivalent to music scores -- and give them a completely different treatment/interpretation. "Darkroom magic" is a time-honored practice. You can take out the offending powerline without breaking the "rules of photography" or artistic philosophy. After all, the image is about the lightning, is it not? If the powerline is a distractor from the lightning, it needs to go.

Sometimes photos need to show stark literal reality and sometimes they become total fantasy compositions bearing virtually no relation whatever to reality -- both are "legit," and so is everything inbetween.

Leonard