The claim that he is best known for something is an opinion and if you can find someone else who expressed that opinion it doesnt change its subjective nature  NPOV is a core policy and your wording violates it  If you think that this would imply that every sentence is opinionated then you have badly misunderstood the policy  Nor does the sentence as I wrote it imply anything about what else he did in his career  I notice that you have not given an answer to my question  what do you think you are adding to the article by forcing your opinion into it  Exactly what is your problem with stating the facts alone without applying a judgement to them