Since rabbit hates the Sanchez's, it would be perfectly legal for him to discriminate against them as long as he doesn't discriminate against them on the basis of one of the protected class. The fact that they are in a protected class (race, religion, gender, etc) does not give them equal protection under the law if all classes are not protected. This is why I have a particular problem with the law dividing people into groups in the first place. Equal protection under the law is not even possible since there are an infinite number of groups of people.
The contract I was speaking of, as in the case of the car lot, is the contract the lot owner has with the city, state and feds to run his business.
The business is his property, but he agrees[contract] to run his business in accordance with the rules, regulations, laws and benefits of these entities.
He is bound[thru contract] by the rules, regulations and laws from the city, county, state and fed.