I never post BS, so this is trivial for me, but I do have some comments.
First of all, it won't work. Jim knows everyone is either too lazy to agree, or is exactly as bigoted as himself and therefore will continue to post BS anyway. The line was an empty, childish threat, equivalent to "I'll stop punching you if you do", or more simply, "eye for an eye". While it sounds fair on paper, it doesn't work in practice.
Indeed, there's no way to stop it. He isn't emotionally weak enough to scare away, even if the entire population turned on him (which again isn't going to happen, because people are lazy), nor is there any way of arguing against his statements in a logical manner -- like the transient response from a brick wall filter, Jim's brick wall head will never stop its culturally engrained political duty.
There is one thing we can try. Jim's threads are some of the most populous. Evidently, getting a Jim reply is some sort of social postrank which induces others to reply. Obviously, a thread started by Jim also carries this postrank, simultaneously drawing in all resident contributors, trolls and trollfeeders.
The obvious solution is to killfile Jim, but as he sometimes posts on topic material, that's not an ideal solution. However, since, like Phil, he cannot be trained, it still has some merit.
If all the regulars here would simply agree to reconsider before hitting the send button, we could see a dramatic drop in the political content. Imagine. Instead of complaining... just... let it be.