Yes, the moon is. :) Most? Tidally locked planets would be around red dwarf stars though, I don't think our sun would work. It looks like Dave planned to handwave it away with aliens.
This is the prompt I would have picked if I wasn't already working on a story with a tidally locked planet. (Earth settles a distant planet but the colony splits, and a thousand years later the two groups above and below ground mostly think the other is a myth.