Hm. Never listened to him reading the book. I do have an interview Waldenbooks did with him and Lynch while the movie was being made, where he pronounces it the way you hear it in the Lynch film. He was also nearly always on-set -- you can see in his face how much he loves seeing what he wrote coming to life. He was involved in a lot of "incidental coaching" sessions with a lot of the main cast, about who their character was, how they felt about other characters, their history, their verbal tendencies, etc. Pretty sure he would have said something if an important and repeated name was being mispronounced by everybody on set.He's the author for god's sake - HE would know how it should actually be pronounced.
I wonder if he changed his position on pronunciation between the '60s and the '80s. But then, I'd figure Brian would know that, and I'm pretty sure he was more than a distant consultant on the new version... Which further baffles me as to the other things they got wrong.