To soak it not to soak...that is the ?

I think the beans absorb more flavor if they are cooked without soaking prior to cooking.
I didn’t have liquid buttermilk but powdered. I still had a lot of cooking liquid so I added the powdered buttermilk with out adding anymore liquid. It made a delicious sauce for the beans.

As written, the recipe seems to be for unsoaked beans; if you soak them, you'll probably cut down on the cooking time and it should be fine, so long as there isn't too much liquid left at the end. If your beans are larger than the small white beans used in the recipe, soaking is probably a good idea.