I flagged his question with the following custom message:
This user posted both his question and an answer (as answers) in this question, so delete both of them.
The flag was marked as helpful. The question was deleted (as an obvious non-answer). However, the answer was not deleted.
So, I decided to flag the answer with the following custom message:
This is an answer to a totally different question that this user asked as an answer to this question (the question was deleted as non-answer but this answer is still here).
However, this flag was declined with the following reason:
flags should not be used to indicate technical inaccuracies, or an altogether wrong answer
I disagree with this decision because the answer is wrong in a different sense: it doesn't attempt to answer the original question. Technically, it is an answer - but to a question that has been deleted as non-answer.
Shouldn't the answer be deleted too?