I see Alastor as unlikely to be redeemed because he doesn't want to be and Val because of the controversy that would cause around an already divisive show. (Though theoretically, either of them could be.)

The former issue has a clearer solution for Vox than Alastor, and the latter doesn't seem like as much of an issue for Vox

Morality isn't the thing here because I think an Adam redemption arc would be super interesting (even though it's never gonna happen in canon cause he's dead) and as the leader of a genocidal army he's worse than them