foxworks: Unless the code is masked, the "ninja" is likely not personally monitoring the site, but has a script running that mines the keys and activates before anyone has a chance to redeem it. Which would also explain the lack of thanks and + 1 reps.
Sounds too paranoic. Once I participated in mass giveaway of keys on other site, where usually nobody do such giveaways, and keys were activated as fast as here. I believe it's just a lot of people on forum, even not logged in, just waiting for keys. Sadly, there is no statistics, available to public, about how much users and guests reading this thread now.