The article doesn't mention it but talking about economics is differently also part of AI ethics.

AI ethics helps you understand the power Elon musk gets if he tweaks the twitter algorithm to promote posts he likes and shadow-ban posts he dislikes.

And the Koch bother was deeply involved in the Cambridge Analytical scandal where machine learning was used to manipulate voter behaviour in order to get Trump elected. Even with Cambridge Analytical gone, roomers still go that Charles Koch and a handful of his billionaire friends are training new models to manipulate future elections.

So even if evil billionaires are all you care about you should still care about AI ethics since it also includes how to protect society from people who use AI for evil.