Hey, progress! Those who defend Nazis have actually answered the question.
I'm gauging that the answer seems to be "because of free speech, and because violence is bad."
As to the former: Do you then admit to valuing freedom of speech and "diversity of thought" over peoples' lives? The question here is: which do you guys value more, the abstract concept of free speech or the very real and pressing matter of peoples' rights to live?
As to the latter: A hypothetical. If there was a murderer at a party who locked all the doors and started stabbing the other guests, how would you react? If somebody who tried to use civil dialogue to reason with the murderer was simply stabbed, how would you react? If eleven other guests attempted this same method of preventing knife murder and were equally stabbed, how would you react? If the thirteenth guest then used force to prevent the stabbing from continuing, how would you react? Would you hold this guest's hands behind their back and yell about the right of the knife murderer to civil discourse?