Obviously, an article in the National Review isn't worth much as evidence by itself. But it quotes reputable scientists who have gone on record as saying they believe he is stonewalling their requests to see his raw data.
The CRU has acknowledged that the files are genuine. In one of the emails, Phil Jones brags how he unethically manipulated the presentation of his results (Nate's words, not mine). And we might not be able to go back and check his results against his measurements.
It seems to me that this would be a good time for an audit of the climate change data. Our first priority should be maintaining the integrity of the scientific process, and in this case that means getting rid of the appearance of impropriety. It's wrong to hold back scientific criticism because of the way we feel about whichever group is currently using the scientific consensus to advantage in the infinite clown fight that is partisan politics.
EDIT: this post went through several versions, most of which were bad. Sorry to those who replied to something that's gone now.