>Voices that call for repression of rights for certain parties should be silenced.
This is going to sound unbelievably pedantic and frustrating, but... What about the right to free speech?
1. Vulnerable groups should be protected. If my speech has historically led to The Right To Life of others being violated, then their right to life is much more important than the freedom or protection of my speech.
2. The right to free speech is a legal device to protect you from the government coming into your home and taking you to a gulag for stating certain things. In no cases are your rights to speak being violated, you can speak these things privately within your home. However, when in public and on private land, we need different rules. Just as public indecency violates your right to wear or not wear whatever you wish when out and about, so do hate speech, libel, slander, and defamation laws also restrict what you can state in public.
3. I wonder why people only bring this up with respect to social justice discourse. A couple of months ago, a person was taken to court by someone in government for laughing at them during a speech. Just this week the CDC was banned by the government from saying "evidence-based" and "science-based". And yet the social groups (on 4chan, twitter, facebook, HN, etc.) that frequently claim for freedom of speech with respect to social justice is curiously silent about examples of actual government repression of speech. This leads me to believe that there is a certain disingenuity when this is used as a rebuttal.