I too don't think there is any "moral obligation" involved but I did feel it was perfectly fine to point out what I did. I quoted their "I work for MS" to provide the context for my comment, nothing more.
Sorry, but that's definitely not accurate. You quoted it as part of a personal attack: implying that someone was lying about making a mistake, imputing sinister motivations to them instead, and adding a name-calling putdown into the mix (accusing them of being inside a "reality distortion field", as if you know more about their world than they do). All that is clearly against the site guidelines: https://news.ycombinator.com/newsguidelines.html.
You are insinuating astroturfing with no evidence other than "I work at Microsoft" and your personal, albeit somewhat justified, belief of "MS bad". It's not a constructive comment.