I think this factcheck could have a lot more in terms of confirmation, while including that New York Times is a trustworthy publication is generally true, any news source can be wrong. In the original article by the New York Times, they cited 7 anonymous sources who were present at the private meeting during which Donald Trump referred to Kamala Harris as a slur. Additionally, by checking the sources, author credibility, and repetition of the news story by other news stories makes your argument that much stronger.