I don't know Martin's specifics for macronutrient breakdown, but unless you are insulin resistant a large'ish amount of carbohydrates within an hour of training (heavily) is actually productive. I have also noticed that if I eat more carbs after lifting (200g within an hour usually) I am much leaner and less "puffy" looking the next day.
15% is definitely low enough. Follow one of his training/eating protocols (they are on his site somewhere) for at least 2 weeks and see what happens.
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