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.
I'm sure you didn't intend it that way, but we have to go by effects, not intent (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...). Intent doesn't communicate itself, so the burden is on the commenter to disambiguate (https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...).