So if you use snowfoam, does that eliminate the need to use a citrus cleaner?
Yes and no.
Basically, you should pre-wash the car to loosen any dirt or grime that might be dried in. Snow foam is used for this purpose. Now detailers are finding citrus degreaser to be just as good if not better than the usual snowfoam degreaser.
Confusingly, you can citrus pre-wash to use in a snowfoam.
When the weather's a little better for detailing and I've got time, I might get some citrus degreaser and use a foam-head spray to apply it as a pre-wash and see what happens.