PARIS—Naomi Osaka was fined $15,000 at the French Open for skipping a post-match news conference after her first-round victory Sunday—and threatened by all four Grand Slam tournaments with stiffer penalties, including being defaulted, if she continues to avoid meeting with the media. The fine will come out of Osaka’s prize money and was announced in a joint statement from the president of the French tennis federation, Gilles Moretton, and the heads of the other majors. Osaka returned to Roland Garros after skipping the trip last time, turning in a mistake-filled 6–4, 7–6 (4) victory over 63rd-ranked Patricia Maria Tig at Court Philippe Chatrier on Day 1 in Paris. After the 2020 French Open was pushed to a September start with a limit of 1,000 spectators per day because of the coronavirus outbreak, things were closer to normal Sunday: It was a sun-kissed May day and more than 5,000 fans were …