[the_ancient]

These roommate exceptions are definitely needed for a verity of reason. Living with someone is deeply personal as such you should be able to discriminate more that a simple commercial lease arrangement, however from the story I doubt they would apply as the author states "crissie" is in California and not on the property, or at least it is not her primary residence, might be a vacation home, or it might be pure rental income.

[ChoGGi]

Actually the author (as well as Steltek just above you) stated Crissie is the friend he is going to visit, not the Airbnb host.