Matt,
I live on Oahu but I was just in Kona, actually Waikaloa area. We just dove behind the hotel. It was a little rough and had to swim through some minor surf, but there was lots of fish. We stayed in the <40 ft. as my partner is new to spearfishing. I would assume your friend could get in some nice shore dives. He should find a partner though. Maybe some of the Kona members here could take him out on a dive. He should also learn which fish are the better eating fishes as it would be a waste to shoot what he won't eat. Keep an eye on the tides, this week is full moon and there are steep tides and sometimes stong currents. Generally speaking, the smaller tides, or slack times, have less current. Tell your friend to call or stop by Blue Water Hunter in Kona, and maybe they can give your friends some tips on where to dive.