Well, there isn't much you can do now so anything we say here would be kinda of pointless.
But my opinion if you want to hear it. (playing devil's advocate a bit)
1 - Not shooting RAW, that's not a bad thing or end of the world if you can nail the shot all the time. It is like shooting film in a way, you just don't get the latitude as you do with RAW. Shooting Jpeg does not equal a bad photographer, it just means he will be in more trouble should be miss the exposure.
2 - 28-70 is a good lens, bad CA does not make the photo bad automatically. You can still take a decide photo with a kit lens. Since it is California in BRIGHT daylight, he doesn't need the 2.8 so shooting at 4.5 in a kit lens would work too.
3 - I guess he wasn't paying attention with the histogram or even the LCD when shooting. My guess he stuck it in manual and over did it. If he had shot in Av then the camera would have compensated.
4 - Things like planes and birds flying overheads are difficult to shoot, you need a REALLY wide lens to make it feel right, and the couple should be in some kind of pose (either kissing, or looking into the distance), if they are just idle then it's just a bad shot regardless what is overhead, same with birds.
5 - I would still try to process the Jpeg, you can probably recover more than you realise.
6 - You said "you ASKED for candid style shots" Is that what he is good at? or is this want you wanted him to do but his portfolio doesn't show he does those?
