Parasite reveals that he doesn't retain the knowledge that he absorbs from other people. This explains why he doesn't remember that Superman is Clark Kent.
Parasite assures Superman that the janitor's closet is a "dead-end". This statement has a double meaning here, because Rudy worked as a janitor before he was transformed into Parasite Parasite also reminds Superman that he absorbed his memories in that episode, including his secret identity.
Angela Chen puts her own spin on several of Jimmy's past encounters with Superman, including crediting him with saving Superman from the Parasite which is true.