I was asked this question on Facebook today.
Yes, definitely! The protocol is exactly the same for fearful dogs who are not barking as those who are barking/biting. One change is that you can also reward approach behaviors some of the time. But I like to let the dog still check things out fully, so I often still wait until the dog disengages before saying "yes" and walking away.
As a matter of fact, I used BAT on myself this morning when I was swimming in a pool in Australia. I have a 2-day BAT seminar in Cairns this weekend, so I'm here early to get used to the area and rest up before the seminar. There was a dark shape in the bottom of the pool and I freaked out and swam away. I got out of the pool and wasn't 100% sure it wasn't something deadly (seems like everything can kill you in Australia!). So I approached and retreated, got the info I needed, and got back in the pool and continued a few more approaches/retreats. I wanted to make sure I didn't have any remaining fear that I'd have to deal with tomorrow.
Knowing I could escape at any time made me comfortable going closer to see what it was, so I could relax. The water was not still (there is a waterfall) so I had to put my face to the water to really get the details of what was lurking under the water. The behavior of approaching the dark spot, looking at it, and retreating helped me calm down. The two important aspects were the knowledge that I could escape and the ability to see what was really going on. Information and control of one's own safety are powerful tools for rehabilitation.
p.s. It turned out to be a mass of leaves by the drain. And now you can relax, too. See how powerful information can be?