After talking with the guy, I thought for a minute about what might be the consequences of a law making it illegal to fire someone for being gay. Whenever I think about these issues, I first like to ask: what is the status quo? Do we live in a country where companies make it a policy to fire people for being gay? What currently happens to companies that have an overtly anti-homosexual policy? I believe the honest answer is that Chick-fil-a is the exception and not the rule, and that the vast majority of businesses know that bigotry is not profitable in the 21st century. So given that the problem of companies firing people for being gay is relatively small, the benefit of passing a law making that illegal would likely be small, too.
But what about unintended consequences? Employers like to be able to fire people at their own discretion. They want to be able to fire people for being abrasive, annoying to work with, dumb, whatever. When you make it illegal to fire someone because they are gay (or a minority or a woman or whatever), in effect you make it difficult to fire that person for any other reason. Unless you have carefully documented reasons for terminating the employee, you risk getting sued for discrimination. Despite its good intentions, the likely unintended consequence of such a law would be to make employers less willing to hire someone they know is gay simply because it will be more risky to fire them later.
"The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design."