Plyxa - Are they legit?

Okay guys,

So basically I traded a key I had laying around for this copy of Thief Gold GIFT, but to my surprise the gift came in the form of a link which leads to this website "Plyxa". There I have to write the Steam Profile URL and they claim that they will add the Steam user as a friend and send them the gift. I don't know what to feel about this... but from what I gather, they are legit. Can someone prove me wrong?

Anyway, the gift is yours to claim if you want it. I just thought I'll have it in my steam library and use it for future trades (as I already own the game), but in this format.. it's not that usable and I doubt that other users will be willing to trade with me this way.

So if you want it, just say so and I will add you to my friends list and send you the link so you can get the gift.