it's the opposite. he said that jogo wouldn't know, cause he's a curse
Ye.
He said "I thought you would know this. But I guess not since you're a curse spirit"
Meaning, sukuna did think that jogo should have known what it was at one point.
The sorcerers have no idea what Open is. Neither does curses.
So I think the only group remaining that would have some idea is beings like Sukuna. Sorcerers/curses turned in to cursed objects and traversed thousands of years in to the modern age.
I think it has something to do with becoming a cursed object.
Which makes sense cause it's similar to cursed tools.
We saw Nanami's 7:3 technique was ingrained into his sword and Ino is using it now.
So, by becoming a cursed object akin to cursed tools, Sukuna was able to ingrain CT's other than his own on to his body.
That's my theory at least.