A fair point, but I think Popper addressed that fairly well - by saying suppression of speech should only come in if those expressing intolerant views are in positions where it is conceivable they could act on those views. When the Oklahoma City Bombing happened in 1992 there were 6 white supremacists groups in the entire united states with a combined membership of less than 5000 people. In those circumstances - you don't suppress their speech, they aren't a significant threat. The occasional terrorist bombing is the price for a free society. Today there are over 700 such organisations and membership runs into the millions - they played a significant role in the results of the last election (indeed the ANES study which is the most empirical election study in the US for decades found that without them Trump could not have won). This changes the picture. Now, that speech has the capacity to translate into large-scale atrocity - tomorrow.