I believe I have on several occasions, including here
To the Greek reader, the intransitive verb is assumed due to the εἷς γὰρ Θεός. εἷς, is 1) an adjective, which tells us something about the noun to which it is predicated. Thus the reader would instinctively say the noun/subject (predicate nominative) "is" X. 2) The Greek has εἷς as the first word in the sentence, which many times is an indicator of the importance of the word in the author's mind. It reads very similar to the Shema of Duet 6:4, in which אֶחָֽד is identical to εἷς and the verb is implied. "Hear O Israel...the Lord is one!" I cannot help but think that this was part of Paul's thinking in 1 Tim 5:2.
In English, however, to write "one for God" is meaningless without a verb written into the phrase. Does it mean "one is/was/ for God"? Is "one" an adjective or a nominative? It is the Greek syntax that determines how we should write it in English, namely, "For God is one!"
Finally, we do not accept doctrine based on a non-existent verb because the verb is syntactically implied in Greek, and because other scriptures (Heb 8:6 et al) tell us explicitly that Christ is a present tense reality mediator.