Tim Cook's point carries over to customers as well. For me, knowing a company is taking a progressive stance on human and civil rights goes a long way towards how I view them.
Maybe not (at least not immediately), but if something is "good for business", it must confer some competitive benefit. Otherwise what does "good for business" mean, exactly? And the competitive benefit is really enough to ground the question I was asking.
Cook isn't trying to make a persuasive factual argument, he's making an endorsement, the power of which comes from his role at a major American firm. I have no doubt that he personally believes that workplace equality is beneficial to business. The argument against assumes that he's a bloodless psychopath who is willing to condone discrimination as long as it improves his bottom line.
If you're a white heterosexual male with no disabilities you don't care. carry on, business as usual. If you're not white, or not straight, or not male, or if you have some kind of disability, or etc etc you care because you don't want some fucking arsehole denying you a job purely because of that difference.
That said, I'm not sure I understand your position; are you saying you want the government to force the arsehole to give you a job? Do you really want to work for that kind of arsehole? Wouldn't you be better off getting a job from someone like Tim Cook, who doesn't need to government to force him to uphold workplace equality?
Senate Vote on Workplace Bias Against Gays a Test for G.O.P.
Perhaps it is risky for Apple to take such a stance, but it is most certainly good for Tim Cook!