So many moments I don't understand what is going on lol. And why he didn't just use his wish for him to still remember when he is working as a shinigami.
even if it was allowed (probably wouldn’t) the whole meaning of all the time he spent with the deceased would be made empty
the message he takes away is that making people happy is still worth it, even if they‘re no longer living and none of those changes remain, and even if no one remembers — even himself
so if he wished to remember it’d be like saying everything he said to Hanamori and all they did together was a lie