Enes Kanter, the Boston Celtics’ new center, isn’t the kind of athlete who is content to shut up and play. When LeBron James seemingly sought to placate China, chiding Houston Rockets general manager Daryl Morey for a tweet supporting protesters in Hong Kong, Mr. Kanter tweeted, “Wow dude,” accompanied by a hand-to-face emoji. For good measure, he added “SMH” (shaking my head) and a barfing emoji. Last week, Mr. Kanter took to Twitter again to lambaste Rep. Ilhan Omar (D., Minn.) for voting against a bill to place economic sanctions on Turkey for its military offensive against Kurdish forces in northern Syria.

Mr....