If, because it does not have adequate main bonding, 'something' in the room may be at a different potential to the exposed-c-ps in the room, then that 'something' would be an extraneous-c-p, which required attention to its inadequate main bonding. If you are going to suggest that everything in electrical continuity with that something (quite probably every pipe and every protective conductor in the building) had become an extraneous-c-p, which therefore required bonding, it would be both silly and unnecessary.It's a metal bath. It is in the room. Unlike the door handle and the spoon it is electrically connected to something which can be at a different potential to exposed conductive parts in the room. Why is it not an extraneous-conductive-part?
If, by adequate bonding, the pipe is rendered 'safe to touch' (at the same time as touching an exposed-c-p), how on earth is a metal bath electrically connected (well or badly) to that pipe going to be unsafe to touch?
This is why we have to main bond 'true' extraneous-c-ps close to where they enter the building. Once that has been done adequately, the risk of a potential (other than that of the equipotential zone) being introduced into the building is 'eliminated' (minimised) and one therefore does not have to consider every 'secondary' conductor (those in electrical continuity with the main-bonded true extraneous-c-p) as being an extraneous-c-p.
Kind Regards, John