Indeed, currently Where Used feature in all Desktop Clients (Xmetal, Oxygen, or Pub Manager) is always showing the last version of the object in which the referenced topic was used.
Just in case, to bring clarity, the last version of the object in which the topic is used does not mean that this version is the current last version of the object.
Organize Space does mention all versions that reference the topic. However, it also does not specify if the current last one mentioned is a real last one.
Behavior in both types of clients Desktop and Organize Space is by design, we do list all versions that have a reference to a topic since all of them mention current relevant usage of the topic.
What can be improved as a suggestion: we can add additional information and show if the version in the list is the historical version.