It is good to share needed information with other people
Elliot learned facts about a singer he'd never heard of, later on Johnny asks him about the same singer.
Elliot wants to continue the conversation with Johnny.
Elliot realizes that while that singer is unimportant to Elliot, it's important to Johnny and thus tells him about it.
Elliot doesn't tell Johnny about the singer because Elliot doesn't care about the singer.
Johnny is excited to hear new information about his favorite artist.
Johnny misses out on some important information on his favorite artist.