Here's the relevant part of the timeline (link for those who have the privilege to see it) on that answer:
15 hours ago flag AnswerNotAnAnswer Stephen Rauch not an answer
15 hours ago cleared Simon Forsberg♦ Declined: flags should only be used to make moderators aware of content that requires their intervention
17 hours ago history notice added Simon Forsberg♦ Insufficient justification
17 hours ago comment added Toby Speight Welcome to Code Review! ...
17 hours ago flag AnswerNotAnAnswer Heslacher not an answer
17 hours ago cleared Simon Forsberg♦ Helpful
19 hours ago history answered hallo ihr geilen typen
Let me paraphrase that, along with some extra comments from my side:
- The answer was posted
- 2 hours later, Heslacher flagged the post as Not An Answer
- The flag was handled as Helpful by Simon
- At around the same time, Toby added a comment, signaling to the user that the answer needs work, and Simon added a post notice, reinforcing Toby's comment
- 2 hours later, Stephen flagged the post as Not An Answer, and Simon declined it
I agree with the decision to decline the second flag. The post notice clearly indicates that a moderator has seen the issue, and acted on it. There's no need to bring this to a moderator's attention again, when the answer existed for only 4 hours. The issue is hardly urgent, and 4 hours may not be enough for the poster to react in response to the comment.
If you see that a post has been handled, please don't flag it again for the same reason, unless you think the issue needs to be revisited. For example, if the 2nd flag had come 2 days later, I would accept it as Helpful and delete the poor quality answer, thinking that the answerer had plenty of time to react, and didn't, and it's justified to trash the answer.