You might want to tell your neighbor to get a normal sized polespear. Shorter spears can be a bit more dangerous because you can accidentally shoot yourself. And to accommodate for a youngster, you can get a longer, thinner band and as he grows and gets stronger, you can increase the band thickness while sticking with the same spear.
I would recommend a one piece, lightweight, aluminum, ~6ft pole. The one piece is more durable than the screw together "travel" spears. The lightweight is handy when you have a less powerful band.
Anyway, those are my thoughts on the subject!