Free speech isn’t a real thing. Every society throughout history has drawn the line somewhere, even ones that claim to have “free speech.” The US constitution had been in effect for less than a decade when the first laws restricting speech were passed. The only legitimate argument is about where the line should be, not if there should be a line at all. Even if you’re a “free speech” person, I assume you agree that csam shouldn’t be allowed, which means you do have a line.