You know what? I'm going to go out on a limb here, and suggest that there is incredibly real possibility that you're the guy responsible for this. And with every post you make in this thread, I'm getting closer and closer to hitting the nuke button on your account. Your consistent defense of, "Hey, this wasn't really a waste of time - it's great that you did all this work" is simply not resonating with me. Sorry.
So - I'm just going to say this, and I'm going to leave it: ALL of this was a complete WASTE of f*cking time - take my word on this! And once I firmly and fully identify exactly who it was in this community, I promise, they are GONE from this website for good!
I have enough clues to work with, so it's only a matter of time... :)
Don't threaten users; don't accuse people of causing harm when you have no proof.
If you have been designing and implementing tools/features to limit spam message, and you've done a good job, it shouldn't be wasted time.
If you have designed your tools to be flexible enough to mitigate further attacks, it shouldn't be a waste of time.
The site was clearly weak to this kind of attack, and you're claiming to have fixed that.
Unless you are lying, and this is just a bandage fix, the site should be stronger against these kinds of attacks.
That's not a waste of time: it's an investment in the future of this site.
As this site grows larger (adding features, fixing bugs, and improving usability should help with that), these attacks will become more frequent: you cannot leave vulnerabilities like this open to exploitation.
Attacks will happen: it's your job to ensure the damage caused by these people/bots is minimised.
Personally: I see this as your failure.
Honestly, the real waste of time is attacking users, based on nothing but your emotions.