They get to do more or less what they want with the software, and others get to say more or less what they want about that. What's wrong with deciding they've crossed a line, being bothered by that, and warning others? Nobody's trying to get the law involved, or maliciously retaliate against them, or anything like that.
I think you are objecting to OP’s “duty of care” wording which could be interpreted as suggesting a legal obligation. Nobody in this thread is really arguing that open source developers have a legal obligation to do this and to not do that. We are just saying they should do this and should not do that.