But trinitarian Dr. Young tells us: "The repetition of a word denotes the superlative degree, e.g. ... Isa 6:3." - Young's Analytical Concordance, "Hints and Helps to Bible Interpretation," #18, Eerdmans, 1978 printing. (Examine Jer. 22:29 and Ezek. 21:27. How would the trinitarian 'proof' method work in these scriptures?)
Even if we chose to ignore such explanations of triple-stated words (as the footnote for Is. 6:3 in the trinitarian The New Oxford Annotated Bible, 1977 ed.) that this is done for emphasis, we certainly wouldn't, I hope, insist that anyone (like Daffy Duck finding a treasure cavern) who said "Mine! Mine! Mine!" is really proclaiming his own 3-in-one triunity!
Or, what could be "clearer" than the testimony of Rev. 4:5 and 5:6 that God is actually composed of seven spirit persons! Sure "proof" (trinitarian-style) that God is a septinity.