Yes indeed, Airbnb can do what they want with their property, namely their website and business, and their customers property is not their business.
> if you don't like it then they even outline what you can do in the linked article.
Yes, you can ignore it, or you can move to a competitor and so on. Airbnb simply is not in a position to force anybody to accept guests they do not want to entertain for whatever reason, that's the way they set things up because that is the easiest for them. To now retro-fit a requirement that you can't discriminate is there to look good, not for you to stop discriminating. The only way they could enforce that is by forcing Airbnb hosts to accept all guests without the ability to refuse any of them and that will never happen.