There is a difference between (a) maintaining high code quality and review standards and (b) yelling at people and/or degrading them.
With this in mind, think through the first-order and second-order effects that happen when toxic leadership behavior is allowed, tolerated, or encouraged in an open source project.
Toxic leadership in an open source project, all other things equal, harms the project and the people.
Of course, historically, there are cases where intelligent and committed people exhibit toxic behaviors -- but this is not a pattern of behavior for us to aspire to. Quite the opposite.
I understand that many people (including software developers) struggle in interpersonal interactions. I don't demonize people when they are unaware or lack the tools to treat others with respect. But these behaviors have huge negative effects, so it reasonable and beneficial to have fair, humane codes of conduct to mitigate such negative patterns of behavior.
Linus' insults were always cringeworthy. Sometimes they may have been justified, at other times they were just needlessly hurtful and revealed some sort of weakness on his part. In any case, he always had the power to say no with just that single word.
Log4J doesn't even have a code of conduct in its source tree, though I guess Apache probably has one. You'll get a free Log4j update if you find any instances of it having an impact on the project.
What is your reasoning for suggesting that (i) codes of conduct are in tension with (ii) competence and truthfulness?
Example, please?