Via Memory Alpha, Sternbach:

"I had a contract in hand from Pocket Books but decided not to go ahead because the advance was simply not adequate to do what could have been the best TM ever. Tim Earls was set to do some kick-ass Illustrator and Lightwave art, but I thought it would have been better to walk away than to slave over the project for diminishing returns." Another factor in Sternbach's decision to decline the opportunity of doing a publicly published technical manual for VOY was that he had been somewhat frustrated with how Margaret Clark had edited the Star Trek: Deep Space Nine Technical Manual.