I'll be honest, the terms of this campaign were too vague.
Basically you get part of 0.1BTC for any domain that goes down if you just post an address??? What proof is there that the emails sent is connected to the poster for instance, and what proves the singular humanity of each poster posting an address.
I am not part of the Exch staff/team or advertiser, but if you took time to read the Announcement and thread, you would not be writing this paragraphs. Everything is clear on how they will know who to distribute the reward to.
eXch meant well but I'm sure they didn't completely think this through.
They did think through it so well, you clearly didn't

First of all there's going to be a lot of spam against registrars just to grab a piece of juicy rewards. In my view the ideal scenario would have been rewarding those users who could prove they sent an actually readable and common sense letter to registrars. But that's just my style to be honest. Evidently the spamming worked against some registrars already.
But those registrars actually interested into following procedures may want to conduct an investigation first in which case spamming them is likely to take away from the seriousness of the case.
For your information, two domains have already been brought down within a few days... so, isn't that effective according to you yet?
Those who try to cheat their way through may still receive nothing, but at the end of the day, what matter most if they don't have any notorious phishing domains jeopardizing their service.