I don't know if Mark ships overseas. However that may be, if you need to use that kind of product I'd look for one that's cold-processed. Spray-drying at a high heat could denature the proteins and make them a bit toxic.
But have you checked out Mark's guide to the Primal Blueprint and seen what he advises as a daily protein requirement? Here's the link:
How to Eat According to the Primal Blueprint | Mark's Daily Apple
He's saying there from 0.7 to 1 gram of protein per pound of lean bodymass. If you want metric that's about 1.5 to 2 grams of protein per kg of lean bodymass.
I doubt eating protein in excess of Mark's figures is likely in itself to help anyone add muscle, though I'd be interested to see any data that suggested otherwise.
I think people like protein powder because they can make quick drinkable meals from it when they're on the go. Or sometimes the portability aspect of it appeals: people think drinking a high-protein drink immediately pre- or post-workout will be helpful. Maybe it would be - although even if it is, is there any reliable data to show a can of tuna or a slice of cold meat wouldn't do as well?
In short, I don't think going above Mark's top figure for daily protein requirement is likely to do much for anyone. So I doubt your husband needs to do three good meals a day and then add a shake made from whey protein, too. But if protein powder fits your lifestyle and when and how you want to eat, why not? Just don't feel it's a necessity when there's a new baby and plenty of other calls on money.