[1 John 1:3] That which we have seen and heard declare we to you, that ye also may have fellowship with us, and our fellowship [is] with the Father, and with His Son Jesus Christ.
This would have been an excellent time for John to include the Holy Spirit if the triune concept of a God head was being taught by the Apostles.
They are speaking through the inspiration of God the Holy Spirit. He need not exalt Himself.