I know what they do, why I said better than some key resellers that sell from stolen means, but there's sleaziness and this does break from Steam's TOS and recently there's been devs revoking keys from accounts and region-locked games. We have no idea if this game is region-locked yet, if it is then there's a chance these wouldn't work to begin with for people outside region 2.
Outside of user risk because of changes Steam introduced in the last year, its true that they're not an authorized key reseller and if people want future Tomb Raider games like Rise, which I've heard from many is quite good, then they should support and buy on authroized storefronts rather than the gray market.