I sincerely doubt there are any kickbacks. He's just a DJ on a lot of mailing lists. Jeez, I know he can get under your skin but accusing him of spamming is just mean.
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I
believe the ignore system is more robust on Xenforo in that if you ignore someone you won't see threads started by them. I could be wrong but I'm pretty sure that's how it works.
Edit: See the second and third post (by the developers of the software) in this thread
http://xenforo.com/community/threads/ignore-system.19633/