I recently updated The Cosmology of Tolkien on The Pilgrim Path/Proto-Protestantism website. The link is here if anyone is interested, followed by the additions I made.
Reeves might pursue a different line and delve into the Angelology of the Deutero-canonical books recognised by Rome as well as additional apocryphal works such as that of 1 Enoch. This would be a worthwhile endeavour but I doubt Reeves would want to explore it. The wider implications in terms of theology, hermeneutics and indeed one's understanding of Genesis would certainly generate discomfort and potentially destroy one's credibility within denominational and academic settings.
Regardless, even if this avenue is pursued, the Sub-Creation doctrine advocated by Tolkien is not a product of the Angel-Watcher stories mentioned in these works. Nor does the New Testament reflect such a teaching in its citation and appropriation of these works and the cosmology they represent. In other words, the New Testament recognises certain aspects of the Angelology posited by Enoch and yet one will scarcely find these interactions with regard to angels and men to be positive. Not only does it result in a profoundly condemned episode it also leads (according to Enoch) to cultural exchanges that are also portrayed as wicked and transgressive. There's no concept of angelic-hierarchical sub-creation, nor is it passed on to mankind.
We could explore 'principalities and powers' and the question of the Divine Council as expressed in the Psalms and the imagery of Eden and Har Magedon. We could discuss the multifaceted meaning of Elohim and other terms referencing 'gods' within Scripture but once again I'm sure Reeves would not wish to pursue such a discussion and I'm willing to be corrected, but I doubt Tolkien was the immersed in Scriptural study to come up with that on his own. Rather, unless someone can show me otherwise I would have to still contend that Tolkien's influences in terms of his cosmology are reflections of Neo-Platonic influenced Roman Catholicism and hierarchical polytheism as reflected in the Pagan Western tradition. Rome in its focus on Catholicity has been able to synthesise these various tendencies in a way no one else can. This is not meant as a compliment or something praiseworthy. It's simply a statement of what Rome represents. For Tolkien, Rome stands for Divine Truth and signifies the Spirit's Presence on Earth.