They say you should look at the art and not the artist,

What was Levine's art? He didn't sit down alone with a paintbrush, to make a piece of art that people could look at when he and everyone touched by his abuse was far away. He was a conductor. The whole point of his art was controlling musicians; directing them, teaching them, making them do what he wanted. He did that unethically, and it cannot be separated from the art.