Good. Racists shouldn't be given a platform to further their hate.
Well, as in other areas, there will always be abusers. Drug testing welfare reicpients, for example, is a slap in the face to small government ideals and does absolutely nothing to deter abuse.
The truth is the abusers are the exception, not the norm.
Regulations and legalisation are not unlike a doorlock. It might keep out those who would steal given a free pass to do so, but anyone more determined will make short work of it.
You can't legislate against that kind of abuse, the abuse of a black and white law prohibiting this type of discrimination for example.
It's clear to me that you can't regulate someone out of being a racist prick, an addict, etc. They just keep coming up with a new way to do whatever the fuck they please.
Hoteliers and traditional rental agencies are not to discriminate on a list of things (now including sexual orientation and status). They have, including Trump. And they've also been sued to the gills for knowingly violating it and lost. Simply put, it's against the law to discriminate on basis of race or color; religion; national origin; familial status or age—includes families with children under the age of 18 and pregnant women; disability or handicap, or sex. (Source: http://www.nolo.com/legal-encyclopedia/free-books/renters-ri... )
Does that mean I'm required to let people in my home? Well, no. Just because someone shows up on my property means nothing. If they try to come in without permission, that's trespassing. If they have a weapon, in many states I'm legally able to blow them away. Castle Doctrine is the general description, with unique laws per state ( Source: https://en.wikipedia.org/wiki/Castle_doctrine )
But what happens when both are true, with AirBNB and someone I don't like (Muslim/Christian/Atheist/Black/Brown/Asian/gay/handicapped/dirty/poor/smelly/angry/arrogant/...)? There's the crux.
OK, so seller is allowed to arrange with buyer not to resell the property to XYZ race but the agreement can't be enforced by means of a lawsuit.
And you found this relevant because?