It is reasonable to carve out spaces where particular norms apply, especially when those places have idiosyncratic goals, like HN's goal of "gratifying intellectual curiosity".
It is not reasonable to export those norms outside of those spaces to other spaces that don't share those idiosyncracies.
Some calls to terminate people are, in my judgement, bad. David Shor is a good example. I will use my freedom of expression to say that the people who called for his ouster made a grave and self-defeating error and should be ashamed of themselves.
Some calls to terminate people are not, in my judgement, bad.
HN might, along with the authors of this Letter, hope for a blanket norm against calling for anyone's ouster. They can ask for it; that's their right. But it's not a reasonable expectation, and they can't honestly pretend the norm already exists or that others are obligated to adhere to it because they want it.