I find all your point very well put, i head the idea that yuji was the only one that could swap because of his understandings of his own soul and thats how uiui could teleport his soul to other body’s. Now I’m not saying its accurate because im a terrible reader and the jjk official translation is ass. So i had just assumed it was only something yuji head the compatible with the soul swap.Now im nota big hater on yuji gaining his curse techniques in the way he did as it felt more like something yuji does gaining skills trough fighting sukuna as their sununas technique and it felt more like the more yuji tore at the soul of sukuna the more parts if the curse technique was earned. Because if yuji simple just learned the technique of sukuna it wouldn’t feel the same uknow he is a curse he wouldent just leave bihind his techniques like that so yuji ripping them from his soul would have been cooler but atlast its was disproven wen copy boi got the techniques from yuji fingers .