I don't see any remotely convincing reason for the assertion in the article. Don't protest because 'sport is about bringing people together' or equivalent saccharine bullshit.
I may not agree with every protest issue, but in general, the podium is a great place for protest. It's great to see athletes breaking shallow rules, and incurring personal costs to try to make the world a better place.
https://www.zinnedproject.org/wp-content/uploads/2013/10/Oct161968-mexico-olympics-black-power-salute-mexico-city-mexico+1152_12779808111-tpfil02aw-13534.jpg