I think that when a wealth of other reliable sources don't describe an economist as Marxist, Wikipedia shouldn't give precedence to a single op-ed in the Stanford Daily from 1976.

You're focusing on when the word "Marxist" was removed in 2024, but you might want to consider when it was added to the article (in August 2020, about two weeks after Harris was selected to be the vice presidential nominee): https://en.wikipedia.org/w/index.php?title=Donald_J._Harris&...

You say it was added in August 2020, but the article was created in August 2020.

Not much of an indictment that additional information was added sometime shortly after the article was created.