If the above quote is correct, are there also images of the Holy Spirit in the Eastern Orthodox or are they also prohibited?
The Holy Spirit can be depicted in EO icons, but only in the specific revealed form at specific instances. IOW, the Spirit can be shown in the form of a dove, but only in icons of Christ's Baptism, as it is in this form that the Spirit became manifest at that particular place and time. In icons of Pentecost, the Spirit is shown as tongues of fire descending on the Apostles. However, to portray the Spirit as a dove in any other icon is wrong: the Spirit is not a dove by nature, but immaterial, infinite, indescribable, as is God the Father. God the Son, in taking up human nature, becoming incarnate and living among us, can, and indeed must, be depicted iconographically, as a Child, or as a Man. The iconoclasts, in denying this, in effect denied and diminished the Incarnation.