He’s absolutely a hero and without him the death star would’ve probably obliterated the rebellion (if it even existed without him). His methods aren’t exactly “good” though from the perspective of good vs evil. As we see with Mon Mothma who is maybe a bit naïve and definitely doesn’t approve of his methods. But I think a rebellion needs a Luthen. He knows he’ll be hated by pretty much everyone, but in the end he managed to get so much done. He’s the fall guy so the formal rebellion doesn’t have to get their hands dirty.