I commend the family's efforts but it does seem paradoxal that when you are trying to reduce your carbon footprint you keep animal products in the diet, the biggest source of greenhouse gased in the world. Surely they know that.
Surely you noticed they have 2 kids. A healthy diet for children includes some meat. When they will grow up, they can make that kind of choice for themselves - becoming vegetarians or whatever they like. But until then, a parent's responsibility is to make sure their kids have a healthy diet. And the Johnsons do a great job, don't you think?