How about rather than getting "zero" post count for an OMNI post, you get "-1" or "-5" or something like that. So, once you get to the 100 post minimum, you've got to maintain activity in other forums in order to maintain the minimum post level to continue to post in OMNI. And it would be really great if this could be done retroactively. I think you'd find some long-time posters with 5,000+ post counts suddenly find themselves at a negative 2,000 non-OMNI-eligible post count.

(or maybe I just thought this post would be a good opportunity to get me one post closer to OMNI-eligiblity)