How is that different than someone selling products on eBay or Amazon that were purchased with stolen cards?
G2A is fundamentally a consumer empowering type of market/organization, businesses who sell keys do not want their completely legitimately purchased keys resold, and if you don't think they are going to stoop to painting the people who enable that as horrible monsters, you have ignored the entire history of markets and PR.
G2A has a standing offer to pay devs 10x what any fraudulently obtained keys cost them, and they are making good on that offer here, the fact they are still being treated like some kind of mafia-esque organization in these comments says a lot about the power of PR.
Remember when the RIAA was coming out about the evils of used CDs and was asking congress to make their resale illegal?
We are at that point right now with digital goods, with the majority of people cheering on this blatantly anti-consumer bullshit and painting those that enable fighting it as scumbags
Now they simply (and appropriately) offer to repay proven fraudulent keys and chargeback fees.
G2A doesn't get much good press because many people empathize with indy games devs, and prior to this finding G2A loudly and broadly claimed that there were not stolen keys being sold through their storefront.
What matters is how they address it, and that is being completely ignored in these comments in favor of vague moralizing about the evils of consumer choice.
IMO this should be a congratulatory post "G2A owns up to their mistakes and follows through on their word" ...