How uncharitable of you to write that. I didn't "forget" it. It wasn't relevant to my point. The first line was specific to this situation, but the final two I quoted represent a very universal and timeless position.
In fact, ancient Athens suffered greatly when "silence the voices of the enemies of democracy" became the dominant position in their society:
Universal and Timeless position is a stretch. It is not black and white, it is grey and the first line in OPs comment put context to that grey.
While it would be lovely to have a democracy with an educated rational electorate resilent to hateful demagogues and other threats to the stability of that democracy, we are not there. In that situation you can let it fester or reduce the impact.
Yes it can be abused and we have to be careful. But we are in a Paradox of Tolerance situation.
Rather than state what has already been said: https://news.ycombinator.com/item?id=17702464 is a good summary.
It's not a good one, though.