Earlier quoted context omitted.
It's false. People will not go into suspend mode when not walking; they still burn calories. A very large person would burn about 130 calories walking a mile. i.e. one large latte. And most people who are this large are not at risk of a caloric deficit by burning an extra 130 calories.
Humans are INSANELY efficient at walking. That's why walking and running are terrible ways to lose weight.
https://en.wikipedia.org/wiki/Energy_efficiency_in_transport