I really liked this. Tanjiro has shown time and time again that he is of morally upstanding character. He's not the type of person that would have a moment of weakness and become influenced by the promises of a demon (and its blood). Nezuko was able to hold onto some part of her consciousness that loved her brother and her family, so logically (and as shown visually in this chapter), Tanjiro would have been able to retain his humanity through all the bonds he's made. He's been built up to be exactly the type of protagonist that would straight up tell the big bad: thanks but no thanks.
I also like that this is how Muzan goes out: pathetically struggling, physically becoming a baby and then also mentally when he begins bawling after Tanjiro, refusing to accept death even after he's died. He reminds me of Voldemort in that they both fear death so much they are willing to commit unspeakable atrocities to avoid it, even before they lost their humanity. Sure, his backstory could have been expanded upon more, but the essence of who he is has been laid out already.
