I don’t like the fact that this thread is in self-moderated mode for a new casino ANN thread but there’s archive of this forum for deleted post so not a big deal in case of censoring negative comments.
I don't see any problem with this if the OP's intention is to keep the official announcement clean and free of spam posts. As you can see, the thread is clean of all pointless comments, and no posts have been deleted, even after reaching the end of page four. Finally, all deleted posts can be tracked down using forum tools like Ninjaspace. The casino representative is an experienced forum user and clearly knows what he's doing. I remember him recently posted asking about ways to design an announcement thread.
You are right that the thread is truly free of meaningless comments and no posts have needed to be deleted in a long time and since the casino representative is an experienced forum user and you mentioned his interest in the announcement thread design it seems like he is doing this on purpose. So considering the overall situation there seems to be a logical reason behind the OP's action and it may be in the forum's best interest.