1. It is his attempt to have the last word as EP stated when describing childish behavior.
2. The infammatory nature of his posts is intended to distract from the content of the previous post that cannot rebut. Based on the hateful nature of his posts, an appropriate response would be emotional and inflammatory and therefore sucessfully take the discussion away from the points he cannot rebut or renders his statements moot.
3. In the spirit of blast emailing, his posts and long and distracting and by always being the last post in a thread, tends to hide the post of the person he intends to suppress, kinda like a get-it-lost-in-the-crowd-of-messages approach.
**What I have learned is that once you find out the motivation behind a person's behavior, you are not distracted by the behavior itself and less inclined to become angry because of it. you understand what they are striving for as a goal, eliminate their possibility of accomplishing it...and go on about your merry day.