"Let’s go back in history. It is possible that if there had been no free speech for [Karl Marx] and the [Communist] Party in Germany during the early 1920s – if their meetings and marches had been stopped – they may not have grown in strength and influence. Denying them an opportunity to propagandise, gain respectability and enter the political mainstream might have thwarted their rise to power. This may have prevented the [Communists] from assuming the government of [Russia]. Without [Lenin] in power, the [Ukranian Genocide] and World War Two may not have happened. Tens of millions of lives may have been saved if the free speech of [Communists] had been suppressed early on.
This is, of course, historical speculation. We don’t know for sure. But it is plausible that “no platform” for [Communists] in the 1920s could have prevented the horrors the [Communists] later perpetrated. On these grounds, I would argue that it would have been justified to deny the [Communist] Party freedom of speech."