codesushi42 didn't say it was. It said the system you describe still allows lies, myths, and misinformation to spread. The only mention of moderators was in the context of chastising the poster who calls the misinformation out.
> if you see a lie, write a truthful comment refuting it, that way you can convince people instead of trying to silence
The tools you referred to are tools to silence, so you are "trying to silence" every time you flag or downvote a post. As for refuting the misinformation, I regularly see posts doing this downvoted while the misinformation is upvoted[1]. This is particularly true in discussions on contentious topics. Thus, I'm not nearly as certain as you are that these tools would protect HN from a sufficiently dedicated group.
[1] At least once, because I downvote it and the comment remains black.