I don't see anything wrong with talking about the oligarchs as "kings" as well. I think that language could work just as well with Zuck, Bezos, etc. as it would with Trump.
I think it would have been better if she had used a "yes, and", recognising that the Sanders/AOC rallies are bringing a lot of people out and getting them more engaged, then suggesting using the "kings" language on top of it.
I'm cool with your disagreement. It's not known right now what the best strategy is, and I'll concede I could be wrong on that one. I don't know if it will resonate more to "focus on the worst billionaires" or push "no such thing as an ethical billionaire".