Porn is speech according to the Supreme Court. The minute we ban child pornography we no longer support unlimited free speech. So pretending that’s the line we are still holding is a rhetorical device rather than a helpful contribution to the discussion on free speech. In practice nowhere in the world supports unlimited free speech and we all draw a line somewhere the question is where we draw the line.
Almost no one is a free speech absolutist. Instead everyone is arguing where the line should be drawn. The issue one group has is that the other thinks drawing a line over there isn't actually drawing a line at all.