The rule is that the Abraham Lincoln advisor, instead of providing an action that can be taken repeatedly to take 1 worker, provides an action to take 2 workers but also removes Abraham Lincoln, preventing further use and losing the 3 stability:
If the nation has one or zero ungrown workers and takes the nerfed Abraham Lincoln special action, then the nation takes that many workers and removes Lincoln. This is similar to Yuan Dynasty and Mauryan Empire, and unlike Janissaries. If you have already grown all of your workers, this could be used as a delay move.
Here's a BGG thread on the subject: https://boardgamegeek.com/thread/343196 ... ceredesign