Blacklisting should apply to current giveaways

From the FAQ:

On user profiles, you'll see a button that has a circle icon with a slash through it. Clicking this button will add the user to your blacklist. This means the user will no longer see your giveaways on the homepage, and they will not be able to view or enter your giveaways from this point forward. If the user entered one of your giveaways prior to being blacklisted, their entry still remains valid.

Unless it's a technical limitation, I think it should work immediately, in effect kicking blacklisted users out of current giveaways.

Your thoughts on this?

Edit: Some of the discussion below is about phrasing of my giveaway descriptions/requests, so let's see how alternative & simplified text works. Here are a couple of giveaways to test things out:

"Please DO NOT post 'Thanks' (unless you are the winner)."
http://www.steamgifts.com/giveaway/p0iUQ/the-chaos-engine

"Please DO NOT post any comment unless you are the winner or have something interesting to say."
http://www.steamgifts.com/giveaway/K74dq/mays-mysteries-the-secret-of-dragonville