They are doing this in ‘ peace time ‘ , no reason to do this , unless you are a drug runner/grower , you are running from the law , have or plan to commit a crime , etc .
Pure and total speculation, originating (as you said) from your “suspicious nature, and complete lack of faith in humanity.” As mentioned in the previous post, there are those that just simply want to be left alone. Some are entirely disgruntled with society, and some could even become situationally dangerous if provoked (i.e. simply not left alone to live as they choose, largely apart from society). Some were born with the likelihood of such a world view, others were broken by the society they now wish to abandon. But by itself, that doesn’t make them all dangerous at the level you suppose.
The book Public Secrets on his shelf could possibly support your theory – if there were other similar items there. But it’s much more likely that the person focused on the “dropping out” aspect of Knabb’s book, given the lack of truly revolutionary or militaristic additional reading material. Catch Me If You Can is another clue that this is a very non-mainstream individual that doesn’t want to just “fit in” to general society, and possibly one who might have little conscience — but evidence of drug running/growing, plans to commit some significant crime against society, etc., simply isn’t there.
The fact is, there are people that simply don’t “fit in,” who want to be left alone, who are capable of being a nuisance, but are largely harmless if left alone. Your “suspicious nature, and complete lack of faith in humanity” no more make the world as you see it, than is my world view the definitive answer to how things are. I see zero evidence of any crime, except the technical crime of squatting on “public” (i.e. government owned and controlled) land. I neither celebrate nor condemn the guy. Could you be right? Of course. But that does not make it so, and the evidence to support the theory is simply not there.
"Ye hear of wars in far countries, and you say that there will soon be great wars in far countries, but ye know not the hearts of men in your own land."