Even if we accepted the redefinition of this word, as I pointed out in my own essay on the topic, there is no way to define racism in a way that excludes non-whites.

According to the dictionary, one of the definitions of the suffix -ist is "believer in the aforementioned philosophy."

Saying that non-whites cannot be racist is as senseless as a communist in the United States saying, "Oh, I can't be a communist, because communists have never been in power."

He's a communist because he believes in communism. He might have devoured the works of Karl Marx and Friedrich Engels and is now convinced that communism is the best form of government and that every nation in the world should switch to a communist form of government. And that the only reason communism ever failed is that communism has never been implemented properly. And that if communism were just done right, it would be the most successful form of government in the history of the world where everyone will be happy.

He isn't suddenly not a communist because he doesn't happen to live in a communist country.

I believe in God; therefore I am a theist. Even if I lived in a country where religion was outlawed, I'd still be a theist.

The belief makes the -ist. Not the situation the person lives under.

So, yes, if non-whites believe in systems of power and privilege based on race, they are still racists, even under this odd definition.

Also, the definition is simplistic, because it suggests that whites have all power; non-whites have none. Really?

What about the black caucus in congress? What about affirmative action? Black student governments? Black graduations? Black Entertainment Television? UberEats function of supplying black-owned businesses? What about the ability of Black Lives Matter protesters to burn down businesses, riot, and loot while being cheered on by a complicit media? What about the ability of blacks to cancel whites who have done nothing wrong? For instance, Christopher Cukor, who quite appropriately called the police on Wesley Michel, who attempted to bypass a building's security system instead of waiting for the tenant of the building to let him in?