they can... 1) Ask a new question (link to /help/how-to-ask or one of many meta posts on "I have a similar problem but none of the answers work") 2) Read related questions in the sidebar 3) Search for similar questions
"wait" is... extremely unlikely to register as a valid option for someone who is trying to ask a question via an answer.
Of course, if you wanna get clever you can vary this based on whether the author is answering his own question
the /review canned comments do this sort of filtering
@BhargavRao Review has a periodic cleanup task that goes back and deletes these comments if they haven't been acted upon (post deleted) or replied to. I would strongly encourage implementing something similar here, even if you're quite confident in their accuracy.
So, for example, if the flag is declined/disputed, don't leave the comment sitting there forever.