I favor the libertarian model. Just to be clear, I'm not a Libertarian but I like many points of their philosophy.
Many people are surprised by this because as a black man, they don't expect that I'd argue in favor of someone's right to discriminate but yes. If you want to discriminate, it should be legal BUT you have to face the consequences of that decision.
I suspect that the vast majority of the people I know, of all racial backgrounds, would refuse to do business with someone who mistreated me just as I would refuse to do business with someone who had mistreated them.
Being that this is AirBNB, a private entity, I like it. If you're going to discriminate, they will not do business with you.
The power of the Free Market at works.