If he wants fretless, let him have a fretless. The worse thing that could happen is that he becomes discouraged and drops the bass, but on the flip side, you can take his fretless and add it to your stable.
It's like learning on any instrument w/out frets. My god... if violins had frets... I'm not sure if that would have made things any easier for me cause I still suck at playing it!
Fender Active Precision Bass Special