Modern sheep are. If they're not sheared regularly and their fleece is allowed to grow, they end up suffering quite a lot - they are not suitable for living in the wild, and in the other direction, are also not particularly suitable as pets.
Yes, nature is not a thing with intentions, but modern sheep are a combination of natural processes and humans (who do have intentions) meddling with things.
It's not like dogs who have evolved to live with humans and are generally treated well.
Also the article's point and general theme seems kind of weak :
>In line with this, several decades of observation show that orcas are not naturally violent towards humans. There are no recorded cases of a wild orca killing a human.
This implies (and the surrounding text) - that this behavior is a result of captivity changing their behavior.
How often do orcas and humans meet in a setting that would allow them to harm a human in a similar way they would - say a penguin ? Would it be plausible that they would do a similar thing in the wild in a similar setting given enough opportunities (since trainers interact with them constantly) ?