Most thru-hikers will tell you to don’t camp close to roads...may sound strange to some but i agree with it.
I've heard the same -- both because of the danger and the desire for solitude. Thru-hikers may not want to handle all of the questions and bonhomie from weekend hikers who are in the shelters.
However, aren't you allegedly 'required' to sleep in shelters rather than along the trail?
When we talked about later one of my friends asked me why the guy seemed so excessively nice to us.
"Just look at us," I said (we had been in the woods for three days without a shower, shave, or anything of the sort -- and some of us include various and sundry military equipment in our hiking/camping gear) . . . "That strange dude is probably a serial killer, but one look at us and he could barely keep from crapping in his pants."
My rule of thumb in the outdoors is to make sure the group I'm with looks almost like something out of a Mad Max movie. The best defense in a situation like that is an aura of borderline derangement.