He’s offering advice that differs from what Reddit does in practice. They absolutely ban content rather than behavior. Try questioning “the science” and it doesn’t matter how considerate you are, you will be banned.
He covers that further down in the tweets, near the end of the thread. He doesn't necessarily agree with the Reddit way of doing things, but it has interesting compromises wrt privacy.
Because no one has developed a moderation framework based on behavior. Content is (somewhat) easy, a simple regex can capture that. Behavior is far more complicated and even more subject to our biases.