Threaded view doesn't help, because the subject of the email depends on what the reporter types.
As Jeff said, just do it his way. When you report spam, then respond to the spam with a single message that says "Reported." If a better solution is implemented, you'll be told, and not have to do it anymore. But until such time, what Jeff says, goes. I woke up this morning with 8 emails that didn't get sorted into a threaded display all about a post that wasn't there anymore.