You didn’t read the article. I did. You also apparently didn’t read the TLDR bullet points. I did. Let me get the excerpts for you:
They argued in a lawsuit that low-income and Black voters would be confused by the system.
In a lawsuit filed earlier this month seeking to block ranked choice voting in Washington, DC, the local Democratic Party argued that implementing the system would be particularly confusing for voters in predominantly Black areas.
The lawsuit notes that in elections for at-large seats on the DC city council — where voters can currently choose two candidates — voters in Wards 7 and 8 are less likely to cast a second vote, a phenomenon known as "undervoting." "Many of those voters report their confusion about selecting more than one candidate for what appears to be the same office," said Wilson in the lawsuit, arguing that implementing ranked-choice voting "would introduce an additional layer of confusion to the electorate.” // “I have a similar concern for seniors and persons with disabilities," Wilson added.
They’re explicitly saying these minorities are more likely to be confused.
About your point about “they can’t be racist because they’re black”… yes they absolutely fucking can. There is zero need to call on race here. “Our constituents report confusion leading to under voting” is all that needed to be said. Tying it to race is…. Racist. Tying it to age is ageist.