I agree that we have to be careful not to play “good cop - bad cop” (and this has been done in the past).
When we look at the intersection between God and man in the Old Testament I believe we are looking at activities of God’s Word (i.e., the Word….or Son….pre-incarnate).
The reason I believe this are several.
First (and perhaps foremost) Creation was created through and for the Word. Through the Word nothing exists. Nothing has being. The world was created by and for Jesus.
Second, we learn in the New Testament that one can only know the Father through the Son. This is not that the Son is somehow a mode to get to the Father but rather that the Son is an “exact representation of the Father” and that in him the fullness of God dwells bodily. I believe that there is an immutability of God. The God of the Old Testament is the exact same God revealed in Christ.
Third, I believe that in Christ we have the complete revelation of God Himself. There is nothing that can be known of God that is not revealed in Christ. When we see Jesus we see all there is to see of God. We are, however, limited by our human condition. We cannot know all there is to know of God, but that does not mean all that can be known has not been revealed.
So when I read God described in the Old Testament I can be assured that this is descriptive of the Son. In Exodus I believe that it was God who we see in the Logos that is compassionate and gracious, slow to anger and abounding in loving kindness. And I believe it is God who is revealed in the Word who will by no means leave the guilty unpunished.
I do not see the passage as speaking about the Father any more than about the Son in that action (in that interaction with Moses).
Where we may disagree is that I do not believe that Scripture presents Jesus as having the same kind of wrath, love, etc. as God (or as the Father), but instead that the exact wrath, love, etc. spoken of in scripture belongs to Christ.
To use your illustration, I don’t believe we are looking at two “cops” but One God. I see Moses as speaking of the God who is revealed in Christ.
(Sorry for the length, and I hope it helps understand my position).