When someone says "pinned vs screw construction" it doesn't mean the only thing holding the knife together is he pivot pin, it simply means that instead or screws you can remove it uses rivets or pins that arnt serviceable.
Take the spyderco manix 2 LW, it comes in an older version with pinned construction or a newer screw construction. The knife has exactly the same number of fasteners, one is just riveted and can't be adjusted (by the end user, by the factory, by anyone) while the other uses screws.