No, it's not a game mechanic. When you use the Creation Kit(like the devs did to add that clutter) you can set an object to temperarily have no collision(won't move) until the player interacts with it. that is how they get all the clutter(moveable objects) into and on to things in wouldn't normally do with the physics enabled.
It would only be false advertising if they showed the player hanging the tools and likely a mod will be made using skyrim's weapon mounts as starting point if beth doesn't already have a similiar script in FO4