This idea is feasible, we can easily detect spammers/shitposters with date-registered and posts/merit ratio. If we can see a huge amount of post in a short period of time report it directly to moderators, unless it has some sense on it.
Why wait for the shitposters to stop using the forums? Lets take action and start banning them!
I really cannot understand the purpose of such a member making posts here. I mean they mus have realized that they are not going to get any merit points for future posts and thus will never rank up. Adding too many posts (even if they are shit posts) does take some time. Are they using some sort of bot to post these.
One possibility is that they are still hoping that the merit system will be taken back and then will rank based on the number of posts they made. Or they might be preparing the accounts with potential activity to sell later.
I think why they're continue to post even though they won't get any merit is that they are still able to join signature campaign even with low rank accounts, Thus if they use any kind of tool to auto-post something, they will still earn from it. It is really a good thing that they're stuck up to their current rank tho.