When using jam or preserves, I'd imagine the haze would come from the pectin that is very likely to be present in the fruity goo.
All in all, the recipe sounds really good to me. I'm becoming more and more interested in GF brewing because of the dietary needs of my girlfriend, and this looks like something that would be right up her alley.
For anyone reading this that isn't into the metric system, the sorghum extract would be about 6 pounds, each hop addition about 1/2 ounce, and the sugar about 3/4 pound.
The input I would have on the recipe would be: Why bother boiling the yeast nutrient at all? Just add at flameout... I doubt it would affect the flavor of the end product at all, though. Also, if I understand correctly, demerara sugar is about the same as turbinado sugar, and both are kind of similar to light brown sugar. That might help someone who would be interested in trying the recipe but is having trouble finding the ingredients.
Let us know how it turns out. I don't think I'll be able to give it a shot for a few months, but I probably will as soon as I can find the WB-06.