The reasons people find for limiting free speech never seem to end. Apparently, free speech is now out of bounds during sporting events. Or so it seems:
"And in the World Baseball Classic-on March 13, 2006, hidden in a thicket of good feelings and mostly good baseball-Fidel Castro's Cuba reared its ugly head. During the early rounds, on the way to a 7-3 loss to the Dominican Republic, but long before Japan would upend the Cubans in the final, several rowdy fans were causing a disturbance in Puerto Rico's Hiram Bithorn Stadium. These enterprising individuals had coordinated the customized lettering on their shirts to spell out "ABAJO FIDEL"-roughly translated, in English, as "Down With Fidel"-when they stood next to each other. They also displayed a smaller, similar sign with the same message. Before long, however, security guards came to take the sign away. The authorities also demanded that the fans either change their shirts or exit the ballpark altogether.
Source
I certainly think politics should be kept out of sport if we mean by that political interference with sporting events (I don't like political interference with ANYTHING much, actually) -- but these guys were just expressing an opinion. They were even doing it silently, and certainly not aggressively. And if others got aggressive towards them, it is surely the aggressive ones that the police should have been pouncing on.