Well, sure -- that's one way
It appears that 'worker' PIs that are part of the main PI can be disabled. I don't know if that's a good thing. The KFX input and output PI each have helpers that can be individually disabled
However, I still think that the UI for [Get Plugins to enhance calibre] should be internally consistent: [Uninstall] or [Install] as appropriate, [Customize] enabled if available