I made the time and found the energy today. Level-headed and accessible analysis. I am trying to find it in print, but the only opportunity I found was to buy a box set of some journal for 200 bucks; seemed like overkill.
In the view of these authors, theos in 1c is NOT definite (i.e. must not be rendered "the God"), is NOT indefinite (i.e. must not be rendered "a God"), IS qualitative but should not be rendered adjectivally (should not be rendered "divine"). In effect, the text declares that the subject "the logos" has ALL of the attributes of the nominative "God".
I think they say that nothing should be inferred from 1c about the physical relationship between "the logos" and any other person or entity, but that it has already been established from 1a,b that "the logos" has been "with" an entity named "God" since the beginning.
What we are to make of this is not obvious from 1,1, but looking at it in the context of the rest of the NT and OT one might find himself led to some theological inferences that we should avoid mentioning in this forum.