TOO MUCH crap... the soil is probbaly getting hot from breaking down all the organic material you put in... just some good ole topsoil, maybe mix in a little peat moss and roll with it! You don't need all the crazy crap these places sell for a garden...my grandfathers has grown a garden for 50+ years he doesn't buy anything from a Nursery or Lowes for it... keeps a small compost pile in the back of the yard and tills the soil!
This really depends on the natural soil you're dealing with. In Baton Rouge, we have some clay that is a real bitch to deal with. It makes it hard to till and harder to weed. This year I brought in about 500# of compost/manure mixture and a cubic yard or two of sandy loam.
That said, I'm tilling into the ground. He's creating a pot more than a garden. Like you said, he's got a hell of a lot of organic material that is out of the ground in a hot box. That said, those organics are going to drain pretty and the hot box nature of a raised garden tends to dry them out, too. Yellow leaves are usually a lack of nutrients or inconsistent watering. Given the construction of his beds, I'd be willing to bet the water is insufficient.
All that said, those organics should break down this summer and leave him with an extremely fertile bed this fall.