Orca are known to eat moose and caribou. If an orca was hungry and a human presented an opportunity, it might not end well for the human. Just because we have no evidence of humans being eaten by orca does not mean we're off the menu.
It's like the pop-sci adage that "sharks don't eat humans". It's a wildlife conservation meme that is just not true. While sharks evolved to predate certain classes of prey, they're also opportunistic. Even though our nutrient density and anatomical profile might not match a typical meal, sharks will still eat us. Tiger sharks are notorious for this.
I mean these are Great Whites for the most part not Tiger sharks but ... man, I honestly believe that ever single Great White attack was a mistake on the sharks part.
And even for non-humans - there's a great video in there of 4 or 5 sharks all circling a dead or dying seal. One by one they all get in close and then one by one they all take a pass. The seal later washed up on the beach not touched by any shark. The guy behind the video speculated that the seal was poisoned by eating fish infected with a red-tide type bacteria - the sharks just won't touch seal like that.
It's like the pop-sci adage that "sharks don't eat humans". It's a wildlife conservation meme that is just not true. While sharks evolved to predate certain classes of prey, they're also opportunistic. Even though our nutrient density and anatomical profile might not match a typical meal, sharks will still eat us. Tiger sharks are notorious for this.