This makes me 😭
UPDATE: Thanks @nekusoul@lemmy.nekusoul.de for this update: The issue has now been commented on and was closed by the maintainer, where they explained why those blocks would be nonsense. But it appears the OP wants to still talk with maintainer privately about it.
Admittedly the title is pretty sensationalist. The repo activity seems to indicate that the project has some users. It’s impossible to know how many sites or which sites block emails contained in this list and what the impact might be. Even though I think the 7c/fakefilter project is inane, I would hesitate to say there would be no consequences at all.
It’s best to defend legitimate email providers whenever possible. If we don’t, those with an axe to grind get to define the provider’s reputation.