Why don't they just say "We sold it." and have done with it rather than try and deceive people that it's somehow out of their hands how they assign URL shortcuts on their own properties.
Can you imagine what that algo looks like? If this is the case other URLs are getting handed over without payment and there doesn't appear to be evidence of this - which companies have lost their YouTube shortcuts to individuals?
Do we have enough notable cases of either sort to run a comparison? Companies are on average more likely to promote themselves than individuals, so it's not unlikely that an impartial algorithm would rate their notability higher more often than the reverse.
As for what such an algorithm might look like, I suppose it would not be dissimilar to search: determining whether e.g. "lush" is more likely to be associated with Mr. Lush or Lush Cosmetics, and making reassignments when the benefit seems particularly large.
Though if Google does use such an algorithm, it might not be wise for either Mr. Lush or Lush Cosmetics to bank on holding this custom YouTube URL, since someday an even more notable entity for the keyword might appear.
Wouldn't that be applying "don't be evil".