Why does it bother you so much?
Is the dude splattering all over the band? Using obscene/indecent language? Making threats, slandering, etc.? False distress calls?
I'm not familiar with the 20 meter ruckus, as I mostly just listen to the CW traffic.
But I can see how this can get under ones skin. Example: some idiot talks on his cell phone while driving and doesn't realize he is travelling 20 mph under the speed limit and interfering with traffic--not to mention presenting a hazard. Sure, I can patiently drive around him, and even if I used "sign language" he probably wouldn't notice it for the conversation in which he is immersed. It may delay my travel plans minutes or seconds, and no harm is done otherwise, but I find this very annoying.
Same goes for improper use of the bands. Basically, no one likes a jerk, especially a stupid jerk.
If enough hams sent letters to the FCC or whomever about this, maybe something would happen. I can see the potential that 5,000 or even 1,000 cogent letters itemizing times, dates, etc. sent along with tape recordings would have for motivating enforcement.
They have to do something with all that mail, even if it is just to carry it out to the trash. After enough mail, something will happen.
Better yet, get a group together to send faxes. If they are using the traditional* fax machines, it will load up the system and get someones attention.
You know what they say about squeaky wheels.
On the other hand, the tallest nail gets hit with the hammer.

*Newer fax systems receive the document and store it to a hard drive instead of printing it out, and with multiple DID (direct in dial) rollover systems, it is less likely to cause busy signals.