Jjk Curse doesn't work like that, and iirc someone with tons of cursed energy dying is like a bomb to be another curse itself. One probable way tho, is when gege showed gojo peacefully leaving with his friends and that's why he didn't become a curse,. At least maybe that's how he wanted gojo not to come back even as a curse.
Yeah they kinda making gojo seem depressed and hung up on geto and that's the seeming reason he gave up living/fighting,. Considering he killed geto before ( it's quite uncharacteristic I might say but whatever the author wants i guess, since he said he wasn't planning on bringing gojo back at all, though it's really oozing gojo character assassination ) unless he was keeping track of geto's day of death and planning to die that day since he have to "catch up" as per latest/leak chapter.
This is a plot hole. Why? Gojo is Stronger than okkotsu yuuta, Same thing as Sukuna taking over over Megumi or Toji taking over the grandson of priest and taking full control over them instead. In Jjk vrerse theory Gojo should taken over Yuuta's consciousness. And became a curse like Sukuna literally.