It gets quite philosophical, and hinges on whether people basically come to lose their own free will if embedded in a powerful algorithmic communication engine. They disagree with each other and there are definitely weak points in Zuckerberg's argument, but it is an earnest and principled-sounding defence. I think he loses the debate overall, but it's easier to attack his position than propose a coherent alternative.
There is also a part somewhere where Zuckerberg claims that when the platform takes actions such as marking a claim as untrue and linking to a source, that conspiracy theorists just use that to double-down and claim that the platform is trying to suppress their truth.
If he had an actual position or policy, it wouldn't take 30 minutes of clawing at the edges to express it. This is the entire strategy. The invisible line can just be moved a little bit every time and we never have to cross it.