A film provocateur meets the global elite Amid the crowd gathered at the World Economic Forum, Oliver Stone — an unexpected attendee — easily stands out. The filmmaker behind “Wall Street” and “Platoon” has a history of jabbing the political, business and social elite with projects that advance controversial ideas: Think about his films focused on Vladimir Putin, Edward Snowden, John F. Kennedy and more. Mr. Stone came to Davos with another provocative movie, which advocates for an issue long whispered about here but rarely said aloud: nuclear power as a force for good. In “Nuclear Now!,” which premiered at...