I voted for this question to be reopened because the duplicate does not help in answering the question.
I also flagged for moderator attention with the following comment:
This is closed as a duplicate and it probably is a duplicate to some question somewhere but not to the question chosen as duplicate here.
The person declining the flag was kind enough to add a comment or rather a question as a decline reason.
declined - care to suggest a better duplicate instead then?
How would I go about responding to the moderator's custom flag message if care to find a duplicate or not?
Update: The linked question is now deleted and I can only assume that the reason is that I brought attention to it here. It was not a particularly good question but I don't believe deletion was the correct action to take.
Closed questions that are of no lasting value whatsoever should be flagged and deleted.
Before voting to delete, please check that there are no good answers; if so, then the question should be flagged for moderator attention as a potential merge candidate. We don't like to lose great answers!
Also, be cautious when deleting questions closed as duplicates; they can serve as a signpost, directing users to useful answers on another question.