If we eliminate king from the result list I would assume it's plural is removed as well. Bummer, that would mean the latent space algebra in this example has no effect whatsoever..
In fact, the plural isn't removed. You can see the effect by analogizing A:B :: A:?.
For man:king :: man:?, you get [kings, queen, monarch, crown_prince] as the top 4. For man:king :: woman:?, the results are [queen, monarch, princess, crown_prince], with 'kings' as #6.
Of course, your model may vary.