delete unused tags - with exception

I am stuck on something that seems as if it should be simple.

This snippet works and will delete any unused tags:

tell application "Adobe InDesign CS2"
	activate
	tell document 1
		delete unused tags
	end tell
end tell

But what if there is a tag called “TagToStay” in the tag’s palette that is unused but I do not want to delete it?

I would think something similar to this should work:

tell application "Adobe InDesign CS2"
	activate
	tell document 1
		delete unused tags whose XML tag name is not equal to "TagToStay"
	end tell
end tell

I have tried different repeat functions but still with no luck. Somehow I have to get “unused tags” assigned to a variable that includes every unused tag with the exception of the tag named “TagToStay”.

I am stumped as how this can be done, can anybody help me?