I am not saying the guitarist has to do it on his own. But he has an obligation to work to improve - OP does not have to just find songs to make it easy for him. It's good that OP is looking for tunes that will be easier for him. As I said, OP should help him find local jazz shows where there are good guitarists, so the guy has inspiration.
Jazz is not my area of expertise. I played it in high school and college, because that was about the only way bassist could play in school. When I was about 40, the drummer in my rock band asked if I wanted to play with his jazz group. No one did anything but tell me what music they were playing.