Sounds far fetched, but it's really not that hard. Quite recently somebody hacked this for correlating HN accounts with each other and found alt accounts of people with high accuracy. Which people confirmed. And that wasn't even a serious attempt, just a little hack on a sunday night.
In a sense, it's all too late now since all your writing is already out there. But could be good to know for the future.
Or, as I do, consider everything posted to HN to be linked to me. My handle is actually an abbreviation of my full name. I consider HN to be "professional" correspondence.
I know that the site guidelines discourage that, but what can you do.