I thought you might have meant that a statute could not affect an existing contract. I had never heard of that before, but governments sometimes compensate people who suffer losses because of legislative action, so there might be something to it.
I don't want the government to interfere much at all in private affairs, and I don't think "there should be a law against" everything I don't like. I am not sure in this case, but conspiracies to prevent third parties (tenants and ISPs) from conducting business are pernicious. I would never enter into such an agreement myself.