I disagreed with him on this count a few months ago, but I have come to realize that he is essentially correct. The "New Perspective on Paul" is no longer new.
In fact, it never was new (really, it wasn't) for according to Solomon: Whatever is has already been, and what will be has been before. Ecc.3:15a.
James Dunn and his thesis about "works of the law" really being boundary markers such as circumcision, the feast days and the Sabbath? Yuup, Roman Catholic apologists were spouting this idea in the 16th century against the Reformers, who interpreted "works of the law" to mean a certain type of meritorious righteousness (that the law gives life based on one's personal merits, which, by the way, is the scriptural view).
N.T. Wright and his silly idea that God rewards us with eternal life on the last day based on our cooperation with the grace of Christ in producing good deeds? Well, one way or another this view has been promoted by the Roman Catholic church for the last 2,000 years. It is also to be found among the semi-pelagians, certain Anabaptist groups and the Holiness camps (also among some types of pentecostals).
The idea that Paul was really not opposing "works righteousness" in his epistle to the Galatians and the Romans? Catholicism.
The idea that sola scriptura gives you an excuse as a scholar to ignore the last two millenia of exegesis of the pauline letters as if they had practically nothing of value to say? As if your reading and the problems it poses have not already been discussed and discarded long ago? Yep, Anabaptists have been terribly guilty of this from the start.
So Jim is correct, we should not call this perspective "New". We could call it "the idiotic perspective on Paul" or the "philistinic perspective on Paul" or even "the new perspective on Pelagius" or we could simply give them a measure of what they have given the rest of the history of biblical scholarship: a cold shoulder. This is likely the best option.