OP - it might be possible that there's a legitimate key on that site right now, but it would have to have been sold by a Kickstarter backer.
Dear NotAPyramid,
Firstly I would like to commend Ayvah for being very knowledgeable and understanding. Adding on top of the posted information, while fraudulent transactions are very serious, those are only a tiny fraction of the global purchases done at G2A. Nevertheless we take the situation very seriously and we have recently launched a modified version of our strict seller verification system, which should help deter frauds.
If you have any further questions, keep in mind that you can always find additional information on G2A's FAQ page or by contacting us in 8 languages on helpdesk(at)g2a.com. Our consultants are there for you 24/7.
We hope to see you soon again at G2A.COM!
Rob
G2A Team
Somehow I doubt that you're a long-time lurker. So do you regularly do a Google search for "Are keys on G2A legit?" posts so you can helpfully step in with corrections?
