I remember this incident quite well. The difference was this was a one time gesture, a big difference from what is happening today in the NFL, NBA & MLB.
The problem lies in the hands of the owners of sports teams who have zero backbones and spines. All that needs to be done is for the league and the team owners to inform their players, etc., that they are playing for a sports team, not a political party and, that their customers and fans deserve a sports event free of political infection, one side or the other.
If these players are so driven by their political views, let them openly join the Democrat Party left-wing nutcases and then they can rant and rave all they wish to.