He needs to be killed. Period.
We do this with bears who become problems for people. Same for killer whales. Once they get a taste for people, do not release them into the wild.
THEY captured HIM. THEY brought HIM into the human world, rather than allowing him to live in his own environment, where killer whales do not attack people for food.
Perhaps he is pissed that he is living in a swimming pool, and he is attempting to get that point across. He is not JAWS, for crying out loud.
What makes it worse is that this whale has killed three people, and yet they will continue to keep him, rather than free him, because he is worth too much money to them as a breeder.