It goes in my machine all the time - add to soups to give creaminess, use to make smoothies, to make some breads......
We don't use much milk (for coffee, tea, brekkie) so keep powdered milk.
I am not worried about my health, sorry, I should - but I don't think there should be problems.
The yoghurt recipe, from memory, has powdered milk added for extra creaminess?