Yeah, I agree that 'non-literal' is much more complex than Ni v Si. With NTW, he doesn't have any of that 'silly-serious' humour that Si types have, nor any inclination to historical minutiae for the sake/love of the narrative details, and he often (including in the glasses-less video) talks about 'what it means to be human' (which Auburn refers to in the FeNi thread). He does this in the context of humans being the image-bearers of God, and perhaps those who ultimately reject God will reject that image and become something less than human, no longer human (whatever that means). I can't detect much Si in him at all, so I'm still mostly leaning to Ni. I think he has a seriousness and intense-ness, but with gentle-British-ness. His 'concern' look almost always comes with an amped-intensity, and it remains when he's looking away. It's different, IMO, than Si concern.
I think he's talking about the distortion of the soul once the total rejection of God is irrevocably made (damnation/hell), as happened with the fallen angels. They lost their grace and beauty, becoming devils. (Think of how Smeagol became Gollum in the Lord of the Rings after the ring.) Again, seems p. standard to me, speaking as a Catholic. I don't think any of this has anything to do with typology tbh. It's a deeply mystical understanding, which TeSi Tolkien shared.