I believe the reason for the claim of transparency behind G2A's keyblocker list is so that they can make the claim that they tried to fix the problem and if/when it fails they can use it as proof that it is not desired or necessary. This is actually pretty insidious of them to throw out this attempt to "help" at a time when so many indie dev's don't want to do anything with the site, because it's just going to make it easier for G2A to claim that they offered this solution and no one was interested. Then G2A would just be able to claim that all this hatred for their platform is just from a handful of embittered dev's who don't even want to fix the problem.
Now, anyone whose done their research or paid attention to these news stories would know the climate in which G2A made such an offer. However, even then G2A would just be able to claim that if the dev's cared so much about the ethics of the issue then they would have still signed up for the list. Thus while in the moment this tool proposal/list comes across as a pretty empty gesture, there is no doubt that G2A is planning on using this as a way to counter their bad reputation in the future.