I recently flagged the following comment
Are ruler and compass allowed? User64494
to this question.
However, it was declined by the moderators which leaves me wondering when a comment is "not constructive". This comment is the one which adds nothing to the post and in fact even seems a little insulting.
EDIT: So all the people agree here that the comment was "not constructive" in the literal sense of the word but also opposed the idea of deleting the comment. So would I be correct in concluding that a comment is "not constructive" if and only if it is "disruptive"?