Christopher Nowinski was rubbing elbows at the New York Athletic Club one Thursday night last month, when the tweets and texts started rolling in. He was there to speak at a fund-raiser for head-trauma research when Miami Dolphins quarterback Tua Tagovailoa was carted from an N.F.L. game with a severe concussion, the second gruesome head hit the player took in a week.
Nowinski ducked into another room and immediately got to work, posting to social media and fielding reporters’ calls, his voice rising to be heard over the din and inflamed by what he saw as an egregious violation of player safety.