The answer to this question can be found in Chapter Five of this compelling story. In this chapter, Brian begins to take stock of his situation and try and work out where he is. However, as he begins to try and piece together what information he has, he quickly realises that he has no chance of establishing his precise location. He quickly realises, however, that this is not important. In response to concluding that he does not know where he is, note what he says:
Which doesn't mean much. More to the point, they do not know where I am--they meaning anybody who might be wanting to look for me. The searchers.
Brian thus realises that actually, his lack of knowledge about where he is or isn't is irrevelant. He is stuck in the middle of the wilderness and has no chance of walking to safety. What is far more important, and far more concerning, is that others will not know where he is, as it will be them who will be searching for him and trying to find him.