Assets referenced solely in disabled Niagara Emitters are still cooked and packaged

Niagara Emitters, when disabled, appear to be removed from the Niagara System's packaged asset as evidenced by a sizeable reduction in size. However, if the Emitter referenced an asset, such as a static mesh, that mesh will be cooked and packaged, even if the Emitter is the only reference to that asset. Dangling nodes in Blueprint with a hard reference do not exhibit this behaviour.

• Create a Niagara System with at least one Emitter.
• In that Emitter, reference an asset uniquely.
  • Optionally, use a primary asset label to override the chunk ID of the asset. This just makes it easy to confirm it isn't packaged.
• Disable the Emitter that references the asset.
• Package the project.
• Observe: The asset ends up packaged.
• Expected: The asset is not packaged.