I wonder if the lecturer is majored in history or arts. If historian, you should have researched properly on the artist rather than jumping to stupid conclusion. Have you ever reviewed all his works or his background ?
If you are artist, then just look at his works rather than condemning his themes. When university suppose to be a place to open our minds, these lecturers are teaching student to be close minded. It's already a race based university. Now, its even getting worse. But the lecturer wasn't been penalized.