Do you really need a CoC to know someone who says "This code is fucking garbage and you should be ashamed" is an idiot? Do you really need a CoC to kick out someone who says that?
No, you don't. You don't need a CoC for sensible moderation.
Good moderation is a combination of clear, actionable rules, good intentions and wisdom. Documents like Contributor's Covenant do not help with any of that. They're vague, their intentions are debatable, above all they're the exact opposite of "wise".
This way, if enough people filter-out, the person will be silenced. Others, who are more forgiving, would continue to receive that person's contributions.
My rule is, I make decisions for myself and only myself.