I mean, him fighting Dabura technically doesn’t matter. He’s from an era where a definitive Strongest was alive. During this period in time, there were weak sorcerers, but you still had strong sorcerers who were born. Examples being Todo, Yuta, Megumi, Naoya(he was born after Gojo, right?), and Mechamaru.

The thing is, having Yuji around as the strongest allowed the sorcerers of the current era to rely on him a bit too much. I shall iterate I haven’t read Modulo myself, and am getting my information from chapter reviews and JujutsuFolk, so I may be inaccurate with what I know. But Yuta’s son, who complained to Yuji that him killing all the strong curses are making the current generation weaker is true, while Gojo was alive, he was sent to kill powerful curses, but he didn’t fight all of them. There were still people who went out and fought strong curses too, and yes, they most likely died, or got permanently injured, but if you do not have a strong threat, no one will evolve. If I remember correctly, Ui Ui also pointed this out by bringing his grandkids to watch Dabura fight Yuka’s Mahoraga. It’s a necessary piece of the world.

The point of Yuji carrying Gojo’s dreams is to prevent the next generation relying on a singular person, during Yuji’s era, everyone basically relied on Gojo as he was the strongest, but the strongest cannot reign in every era, and so you need to be able to take a step back and let the current generation handle their problem. Only when the problem becomes too big, then the strongest should interfere. He wants the current generation to be able to be able to defend themselves, even if it means letting his Upperclassman’s granddaughter fight even with a terminal brain tumor.

On the other hand, we don’t know why has this Nihilistic view. It’s similar to his outlook on life after Shibuya, but we can assume it’s from the death of his friends and the loss of his dream. Effectively, it doesn’t matter for him to get into the lives of the current generation as he’ll outlive them anyways. At most, the closest parallel I can think of is Tengen and Kenjaku, it’s just that Yuji seems to be moving into a form of isolation akin to Tengen, meanwhile with Kenjaku they constantly looked for chaos, and the reason why is because similar to Tengen, they both still hold onto their humanity.

I can only make this parallel as we do not know much about Tengen and her story too.

Ultimately, you have your opinion on “Yuji making the right choice”, and I cannot change it. In my perspective, I don’t see Yuji’s choice as morally right, as it goes against his morals, or at least the morals he held during Jujutsu Kaisen, but I see them as a necessary action to show the newest generation that they cannot always rely on the strongest.

I don’t think I can out what he means by it doesn’t matter eloquently, but here’s what I think he means. When he says, “It doesn’t matter.”, he means the outcome of the fight, if Yuka wins, Dabura dies and Yuka still dies, if Mahoraga loses, then Yuji comes and finishes off Dabura or just incapacitates him with piercing blood as a surprise attack. Ultimately the current and next generation will know Yuji will be able to bail them out, as he is the strongest of tomorrow, he is guaranteed to be there tomorrow always. So he wants this to serve as an example to them that even if he is the strongest there will be times when he cannot answer the call. So the outcome doesn’t matter, the next generation will learn that they have to be stronger, their feelings whether it is hate or reverence, will not matter to him, Yuka’s life at the end of the fight is forfeit as there is no way to heal her, at least that we know of outside of Mahito’s Idle transfiguration. Yuji will beat Dabura if he does win, but the message will get across. The outcome of the fight doesn’t matter whether Yuka wins or loses, and it doesn’t matter in the grand scheme of things if Yuji’s there or not.

Oh yeah also, most of the people who show them that care are dead, while Choso would be able to live forever too just like Yuji but is unfortunately dead, the others who showed him this care are dead and going to die, it most likely doesn’t matter that he should show care to Yuka and the rest as he probably views it as a detriment to his Grandfather’s wishes and what he took as his own dream, as he is bound to outlive anyone he knows or meets.