Yeah I don't think he should be redeemed, I feel people only think he should because his SM:TAS counterpart was redeemed, except that one wasn't a threat to the multiverse, his ATSV he became way too violent to be redeemable at the end of the film, and judging by the Miles' visions of him he's probably going to be even worse in BTSV, I think him being being trapped in an empty unescapable void would be a perfect defeat for him.