So you would adhere to the original language of property covenants forbidding sale to black people because that was the clear intent of the authors of those covenants? Hey, sanctity of contract!

And do not tell me those contracts were considered illegal at the time they were written.

Contracts can be invalidated (post-hoc) by laws, and both (contracts and laws) can be invalidated by constitutions. Such provisions (in the USA) would have been rendered unenforceable by the Fourteenth Amendment.