Looking for Mr. Wilkinson
The problem with Mr. Terrance J. Wilkinson is that, to the best of my efforts, the only place the quote you mention shows up is here. I have found no sign of his existence under any spelling of "Terrance" or "Wilkinson" anywhere on Google. Now, this doesn't mean anything, such as the possibility that Mr. Wilkinson is a figment of the author's imagination, but one would think at least some other anti-Bush outfit would have snapped this quote up. For someone who apparently attends private White House briefings and discusses them in public to be such a rare bird on the Web is a bit odd too.
If someone finds him somewhere, let me know.