Did you read the article? Here's an excerpt from the discussion about the Peonage Cases:

    While some of these statutes—such as Florida’s sanctions for impudence—went beyond the mere punishing of breach of contract, all of them operated within a thick web of other laws that had the effect of suppressing competition between employers, further restricting the choices available to African-American workers. First, states passed anti-enticement laws that created penalties for those who tried to lure away employees with offers of better wages or working conditions.  Second, emigrant agents, who recruited African-American workers in areas of low employment and transported them to jobs in distant, labor-starved markets, were subject to onerous licensing and taxation requirements.355 Georgia, for example, levied a tax of $500 on emigrant agents for each county in which they operated.356 Mississippi made it a crime to “entice . . . [any] negro” to leave the state.

Courts apply the Thirteenth Amendment to cases involving the "badges and incidents of slavery." Usually, that refers to some form of systematic oppression of African Americans. It definitely doesn't include forcing Apple to write and sign code.