What you're missing is that even though someone was uncivil to you on HN, you needed to remain civil in return. That's the social contract here, and we need it to prevent discourse from degenerating even further.
Given that there is no report button or ability to downvote someone that replies to you (at least not on mobile for me), it is only reasonable to defend myself in that situation.
The ensuing attacker went to my profile, researched me and my business, and personally attacked me because they disagreed with my sentiment.
What is my recourse for action in such a case? Take it on the chin like a wimp? I don't think so.
If you don't provide appropriate tools to stop a tit attack, then you are fostering an unfair and "unsafe" environment by banning tit-for-tat response.
You are turning this community into a one-way echo chamber.
Your recourse is to email hn@ycombinator.com, as the site guidelines ask. Note that I chided that person for what they did, which of course was wrong. Two wrongs don't make a right, though, and you're continuing to break the rules while they at least stopped.
For civil discussion we all need to hold ourselves to a higher standard than the one we perceive other people to be keeping, because the only alternative is a downward spiral, and an accelerating one. If you want to keep commenting here, we need you to internalize that.
https://twitter.com/search?q="you%20spew"
https://www.google.com/webhp#q=site%3Atwitter.com%20%22you%2...
What you're missing is that even though someone was uncivil to you on HN, you needed to remain civil in return. That's the social contract here, and we need it to prevent discourse from degenerating even further.