Wait a sec. Michael "K." Mann is a screenwriter. Michael "E." Mann is an author and, yes, he's a scientist. Moreso than Al Gore.
https://grist.org/article/michael-e-mann-took-climate-change-deniers-to-court-they-apologized/
I assume you're talking about this. Don't like him for taking some people to court? Fine.
You could remove Michael Mann from the equation and still have thousands of other climate scientists to choose from who are saying the same thing.