The trouble is that this will teach him that bass is not what bass is in the majority of songs. Sure you can have all these songs with prominent bass lines - even going back to disco in the 70s like Earth, Wind and Fire, but for the vast amount of playing time the bass is a supportive member of the rhythm department. If it's playing real melodies, it's not bass, even if it's playing low notes. Beware any bass part that spends it's time up in the treble - it's no longer bass. Perfectly valid musically, but learning this style as the 'norm' means that when required to play bass in the traditional role a new player could be lacking in essential skills. I do worry that this modern way of letting people pick songs they like and then learning them teaches nothing at all about WHY they were played.
Let's say the song goes G to C to G again, but the bass note goes G to C then to B, could you guess where it goes next? Can you hear the next note? This is what bass players need to develop. They need to know what to play from listening to the others. Guitarists lead in many cases, and everyone follows. The best bass players can predict where they are going, and play supportively. Learning songs by rote can bring back superb renditions of somebody else's playing, but if you were playing live and the lead singer decided to cut the verse, or by mistake missed the link into the bridge, how long would it take for you to drop back in? Followers need these skills, the leaders assume the followers can adapt. I like to think that it makes the rhythm section more critical than outsiders think!