Intentionally not telling the scorekeeper that you're dropping
This sounds like it needs to be addressed at the local level; it's unlikely to escalate to a point where the DCI will feel compelled to take action.
First of all, if I were organizing this league, I'd deny him credit for Top 8 if he doesn't play - and make sure everyone knows that's the rule.
Another approach - when you're ready to cut to top 8, do roll call of the top 8 players; if any of them are missing, or acknowledge that they can't stay and play, then let that spot pass down to 9th, etc.
And, if a player continues to hurt the events in order to “game the system”, ask him to consider other places to play. (That's polite speak for banning him from the store.) I would only do this after conversations with the player, so that he understands the negative effect(s) from his behavior; if the then acts, willfully and knowingly, to continue to have negative effects? I would conclude that I don't need his business.
d:^D