I don't think selectively quoting to omit "I very much doubt the legitimacy of this story" then commenting "Great source!" is adding anything useful to this conversation.
And the sarcastic remark adds no value, it merely antagonizes the other poster without really explaining what's a wrong with the post, and sets a more combative tone that is not really seen as desirable here. Tone alone can make the difference between a productive discussion and a non-productive debate and HN seems to do a relatively good job at keeping a tone that leads more toward discussions and less toward debate.
I didn't actually say (or mean to imply) I approved of the original post, just that the follow-up comment was of little value. If the best you can manage is to pull a quote out of context and make a snide remark, why post it?
