i'm not sure i will ever get to find out why they took it back. but i think it is very unlikely that it is this post in HN. someone would have to be checking HN very religiously.
You did provide a great amount of detail that could probably be used to identify you. Giving (real?) exact numbers doesn't help either. I would be more careful about disguising career questions in the future, even if this post wasn't the cause.
This is a really frivolous reason to sue. I don't currently want to out the company; if in the future I do, it would probably not be in a random HN comment :).