Domesticated dogs aren't expected to kill people. This Killer whale, OTOH, was simply exhibiting his instinctual behavior. The trainer clearly was cognizant of the dangers of her profession and assumed the liability in choosing to work with wild and potentially dangerous animals.
The whale can't be held culpable for acting like a killer whale.
Lord, you want to use logic in America today.
Then why not yawn and let things go when a bear acts like a bear and kills someone? It is still prudent to save the life of the next victim when we have a known problem animal.
Are there any other fatalities associated with any of the other 50+ killer whales in captivity? If not, then I suggest it is prudent to put this one out of harm's way, one way or the other. It is the outlier, and the reasons why are a secondary concern.
Contrast that to certain sharks, such as Great Whites, hammerheads, and I believe tiger and lemon sharks as well; they have a long-established history of killing and eating people and commercial fishermen and divers, as well as surfers, know it perfectly well and are leery of them. But those same ocean-savvy humans are not particularly concerned when orcas are in the neighborhood because they aren't expected to eat people.
Just FYI.