Template talk:Stub Stagnant
'old' is easier than 'stagnant'... but they are not the same thing. Stagnant says that the page won't be getting changed... even if that would be helpful. It has a 'negative' vibe to keep people from investing more effort in the page.
Also, general wiki contributors won't be using the feature. Since it will only be added to pages that are locked, only an admin will be using it in batches.
Maybe 'Stub_locked' would be better? With the text changed to indicate? Maybe the body of the text should say 'Incomplete and inactive'?