Once again you are alluding to Modalism there that it is one God with three roles or personas, I made sure to address that in my previous rejoinder. As a father, son and brother you are still ONE person so you cannot use US.

The one God on the other hand is three DISTINCT persons so it is appropriate for God to use US. Three WHOS, one WHAT.

And a bigger deal than necessary is being made out of the use of Elohim, yes the word is plural but is usually qualified with a singular verb or adjective. Again all this does is confirm the doctrine of the trinity where God is both a singularity and a plurality. A plurality of persons but a singularity of essence. TRIUNE. TRI (plurality) UNE (Singular).

Thus my original point that if Tanner is aware of the doctrine of the trinity, there is nothing pagan about God saying "US" and even being referred to in the plural as Elohim yet being spoken of as one God in scripture.