> I'm pretty sure you are misreading.
I'm pretty sure I'm not, at least in the way you are suggesting.
> Since (2) applies to AirBnB
(As noted previously, neither 1 nor 2 applies to many uses of AirBnB, where the person offering the rental isn't the property owner but is instead a tenant; but, that aside...)
I was actually responding to your suggestion that (1) applied to AirBnB -- or, more precisely, to a homeowner renting their home out via AirBnB; I was not responding to your argument that (2) applies to a AirBnB -- or, more precisely, to rentals of units or rooms by owners of homes for multiple (but not more than four) families living independently while the owner occupies some part of it (which, again, doesn't apply to lots of AirBnB rentals, including by-owner rentals.)
There are, I will acknowledge, a subset of AirBnB transactions which would fall within the exception of (2) from federal fair housing laws (which doesn't, actually, mean they'd be legal everywhere in the US; many states have much substantially narrower exceptions to state fair housing rules than exist in federal fair housing law.)
> Volokh (a very good law blog)
Volokh is probably the best right-libertarian law blog there is, yes.
> has blogged on this topic a while back
Maybe, but neither of the links you provide are "on this topic", (to wit, the legality of discriminatory renting via a commercial intermediary like AirBnB.) Both are regarding discriminatory listings via hands-off listing venues, which is a very different issue.