Not surprised he was coaching. Serena has a history of poor sportsmanship when she’s losing. If she loses, it’s because she is injured or because the umpire treated her unfairly.
Yesterday she threw a few tantrums. First she screamed over the coaching penalty, then she smashed her racquet, then had another tantrum when she received a one point penalty for smashing her racquet.
Key words in the article are “the tennis legend.” Apparently, she has vested her entire ego in the notion, and now feels she is bigger and more important that the game, giving her the freedom to become John McEnroe. It often happens to athletes whose success overrides any sense of proportion or decency possessed by ordinary humans.