It's only an obligation to the extent that he wants anyone else to appreciate the work. Don't read it as "he should do X" but as "he should do X if he wants oth

It's only an obligation to the extent that he wants anyone else to appreciate the work. Don't read it as "he should do X" but as "he should do X if he wants others to read his proof". Whether he does or not is a different question. I think it's likely that he does, but perhaps he's content knowing that he devised a proof himself. And, for what it's worth, communicating results and impact are both usually part of a researchers job description. That might not matter so much thanks to tenure, but it's still there in spirit.