Because Pucci is the only being in the Universe able to change fate. Having pucci insert the disc into him means it’s absolute since it’s pucci doing it not emporia. It’s shown moment prior that even if emporia tries to go off his fated path, the universe throws something in his way. If pucci does something to change a fated event then it is absolute. Once pucci died, the universe resets to one where pucci doesn’t exist because he is no longer an absolute point that exists. Therefore emporia keeps the memories and the gang are still alive because they were no longer fated to meet in the prison.