There's no standard definition of having a "diseased mind," but I think a case can be made that his sexual compulsions were pathological. He was hardly unique

There's no standard definition of having a "diseased mind," but I think a case can be made that his sexual compulsions were pathological. He was hardly unique in having enemies in eighteenth century France, but he couldn't stop himself from handing his enemies one excuse after another to lock him up, often for crimes that we still find repugnant today. (I don't know what your source is for the idea that he never hurt anybody.) It isn't like eighteenth century aristocrats were held to high standards in their treatment of servants and prostitutes. A man who couldn't live within those limitations would have found the twenty-first century even less hospitable to his compulsions.