This is a opinion because the person wants you to agree or disagree on whether sacrificing personal liberties to protect our country from terrorism is good or bad. There is no right or wrong answer, now if it was something like the Bill of Rights protects are freedom of speech know that would be a fact because you can back it up with statistical information.
sacrificing liberties is unnecessary because there are other ways to deal with terrorism and sacrificing liberties is not useful in anyway against the fight in terrorism, because the most effective way to fight terrorism is not diplomacy, but you must fight fire with fire.
The author's purpose for including this paragraph is to explain the resistance that Branch Rickey willingly took on in an effort to being the process of ending segregation in Major League Baseball. This paragraph serves to explain that there were people off the field who also helped revolutionize the game.