What's the sticking point?

The sticking point here has to do with the psychology of the OT writers. When they wrote passages interpreted by the NT as references to Christ, did they consciously have these Christological meanings in view? The advocates of “christotelic” interpretation argue that at least some such Christological content was extrapolated by NT writers in light of the Christ event. Their critics contend that this threatens the authority of Scripture, destroys the “organic unity” of the OT and NT, and stands in tension with the Westminster Standards. 

http://theecclesialcalvinist.wordpress.com/2014/07/03/how-much-did-the-ot-writers-know-2-the-spectre-of-bibliological-eutychianism/

I'm not a WTS insider, but I doubt that's the sticking point. Now, I don't think Gaffin's explanation was altogether clear, but I suspect this was the sticking point:

It is this point of the entire truthfulness of the history of revelation and Scripture-- involving “the truth, the whole truth, and nothing but the truth,” as Vos says, and critically essential for any doctrine of Scripture, like that set out in chapter 1 of the WCF, intent on doing justice to the unity and coherent harmony of the Bible as God’s own written word--it is just this crucially important point that is compromised or at best obscured by the Christotelic approach to Scripture.  

http://wrfnet.org/articles/2014/06/wrf-member-westminster-theological-seminary-responds-clair-daviss-comments#.U7uBDXO0w00

Gaffin quotes Vos as saying, among other things:

… Reformed theology has with greater earnestness than any other type of Christian doctrine upheld the principles of the absoluteness and unchanging identity of truth…But the Reformed have always insisted upon it that at no point shall a recognition of the historical delivery and apprehension of truth be permitted to degenerate into a relativity of truth. The history remains a history of revelation. Its total product agrees absolutely in every respect with the sum of truth as it lies in the eternal mind and purpose of God...It is an unchristian and an unbiblical procedure to make development superior to revelation instead of revelation superior to development, to accept belief and tendencies as true because they represent the spirit of the time and in a superficial optimism may be regarded as making for progress. Christian cognition is not an evolution of truth, but a fallible apprehension of truth which must at each point be tested by an accessible absolute norm of truth. To take one’s stand upon the infallibility of the Scriptures is an eminently religious act; it honors the supremacy of God in the sphere of truth in the same way as the author of Hebrews does by insisting upon it, notwithstanding all progress, that the Old and the New Testament are the same authoritative speech of God.  

With the greatest variety of historical aspects, there can, nevertheless, be no inconsistencies or contradictions in the Word of God. 

It's the absolute truthfulness of Scripture, and not the "psychology of the OT writers," that's the sticking point. Inerrancy, not hermeneutics. Peter Enns clearly denies the absolute truthfulness of Scripture. Indeed, that's an understatement. 

Unfortunately, Evans seems to be taken in by the "christotelic" verbiage, which makes it sound like it's just a recondite hermeneutical issue. But, frankly, that's the sales pitch. That's a mock-pious decoy to deflect attention away from what Enns is really up to. 

Now, I can't comment on Doug Green, because he's published so little. But, presumably, he was let go for the same reason Enns was let go.