How is a list of his appearances on other people's albums 'trivia'? It's basic discographical information. And as you can see, it's standard content for rappers' discographies. Also, the sources in the album articles must be sufficient if the album listings themselves don't need to be sourced, which seems to be the case per other high quality articles: Bob_Dylan#Discography, Elvis_Presley#Discography, The_Beatles#Discography, etc. I could see a case for sourcing anything that doesn't have its own article, however.