I just went through my copy and I think it is a pretty good book for those on a gf diet. At least 50% of the recipes are gluten free or very easily converted. There is one recipe that uses puff pastry (you can buy/make gf but it is very temperamental), there are pancakes, and a couple that use panettone/brioche that might be trickier (but not impossible) to make gf.
I haven't had much experience with df, so am hesitant in saying either way, but IMO it is not too bad on that front. If he is limiting coconut milk, then there are a few less recipes, but I'm sure there are some df alternatives that might make most of the recipes suitable for those on a df diet, especially if you have the TMX to make nut butter/milk
And for the price, at least it is not the price of a large hardcover book