Dza, I think you should teach him the clean if you can. I agree that the snatch is a little easier to teach and learn, so I say go ahead and teach him the snatch - then use that technical foundation as a basis for teaching him the clean. The snatch alone is certainly better than no OLs at all, but I think both the snatch and the clean are essential to a serious athlete's repertoire.
IMHO, the arms-up receiving position of the snatch does not necessarily translate into basketball-specific strength. I think the difference between snatches and cleans is significant enough to necessitate teaching him both, but if you only could teach him one, I'd suggest you make it the clean.
Nothing I know of matches the clean for developing raw, explosive power over a full range of motion. Because the weights handled in the clean are greater than in the snatch, the clean has a higher potential for power development. Ultimately I think a ball player, especially a young one new to weight training, might see more benefit from raw power development than from a similar exercise that only requires 80% of that power production.
Since the snatch also employs the triple extension, there are many of the same benefits, but the lift is more technical, so it's a little less about raw, explosive power and a little more about timing and control. However, that technique has a variety of useful applications (e.g. absorbing impact, body control, timing the application of force, balance, core strength). Hence training both the OLs will produce the best benefits.
Disclaimer time: I'm just a guy who's been strength training for about 3 years and doing the OLs for the last two. I'm not any good at either, but I enjoy both immensely and have read up a bit on them. I'm not any kind of coach and I don't know much about sport-specific applications. However, I will say that I just went to the driving range yesterday after a 2-year layoff from golf, and I put 15-30 yards on all my clubs, and I got a few drives over the 250-yard fence.
I'm curious to know what kind of program you'll have him on and how it goes. Best of luck to you and your brother.