Were there actually threats? I just googled "Brendan Eich threat" and didn't see anything relevant.
When controversial stuff like this happens, it is sadly common to receive death threats on the internet. Given that employees merely voicing support received death threats, I would be surprised if the CEO did not receive such things as well.
While I agree with you that the HN crowd is not YouTube, there are still many people reading this and sharing with others etc., and since the blogger I am talking about has already been harassed, I don't see a point in drawing more attention there. It doesn't help our discussion anyhow, there are only downsides.