Is the transfer of impurity from the anus to the hand and then its return to the anus via water considered a form of waswas (whispers/religious obsessive thoughts)?

What you have mentioned is a whisper (waswasa); the intention is to remove the impurity from the spot, so that it returns to its original rough state. This is done by pouring water on the impure spot and removing the impurity itself with the hand until both places are purified. We advise you to turn away from these whispers and not pay any attention to them.