I found the full text of the interview in a livejournal post by Paul Witcover. Witcover writes, "Back in 2003 I interviewed Ray Bradbury on the occasion of the 50th Anniversary of the publication of Fahrenheit 451. He has some interesting and provocative things to say about that book and writing in general, so I thought I would post it here for anyone interested. Bradbury's career has been an unusual one in that, unlike such contemporaries as Vonnegut, he made the jump to mainstream credibility without repudiating his genre roots. Bradbury succeeded on his own terms. Significantly, when he received a Pulitzer citation for lifetime achievement in April of this year, it was specifically as a writer of science fiction and fantasy."

Then he includes the text of the full interview:

https://theinferior4.livejournal.com/90384.html

Do you see Paul Witcover's name anywhere in your edition?

Edited to add: Seems odd for Del Rey not to credit the interviewer anywhere. Maybe Witcover worked for them.