[Manco]

This is true I suppose, but...and this is key here, if the suppression of a dangerous view stops people from accepting it and this causing harm to others, is that good? For example, what if Hitler had been kept in prison and his writing apparatus had been removed, if the NSDAP had remained outlawed and members such as Goering and Himmler never assimilated. The mass suppression of these characters would have stopped World War II.

The problem with this is that Hitler and the Nazis did not merely speak about their views, they made them law and took actions which caused people harm.

As Bullet Magnet said above:

Actions hurt people. And someone who can be persuaded with mere words to harm people was already dangerous.

The Nazis wound up in power because of the political and social climate of the times – Germany was recovering poorly from WWI, and there was a lot of bitterness there. If not Hitler, some other radical extremist would have taken power.

People should always have the right to their opinions, but when they actually begin to cause physical damage that becomes a different matter. There is a difference between suppressing views and preventing them from causing physical harm.

“The right to swing my fist ends where the other man's nose begins.” –Oliver Wendell Holmes