It might just be a correction, nothing more. I've done the same in the past in the interest of improving the original comment. Perhaps it could have been made clearer (e.g., "note:", s/1930s/1920/). I'm not sure you can read too much into it.
When pedantry serves as a roadblock to honest, charitable discussion, I agree :) I've written plenty of comments only to not-submit them, and deleted others right after posting. I've really tried to give people the benefit of the doubt, ignore small jibes if I can, and try to understand where people I may not agree with are coming from. After all, if I can't understand them, I'm not sure I can ask them to understand me. It's a work in progress. :)
PS: And actually, given their other follow-up comment,
Parent's rhetoric is self-righteous namecalling. That does nothing to persuade people, it only makes them come back at you. He/she may think they do a service to people, but they are only turning more people to name-callers. As such my snarky comment was deserved. If that interrupted our moment of collective atonement, i apologize.
what exactly is the point of your comment. do you think you are providing any sort of service to the readers of this thread.
does the fact that the OP was incorrect in a minor part of his comment invalidate the rest of it?
does your comment make you feel superior in anyway?
in the future, when posting a retort please ellucidate.