Another reason could be that it is easier to obtain emotional distance on a decision when you're not personally involved. Believing that something is best as an abstract policy doesn't always make it easy to believe it is best for you.
A third possibility is that he does believe that the market should decide, but that he also believes in taking full advantage of the system as it exists today.
As far as the second point, the free markets no longer operate that way, marketing has emerged as a white washing effect for any ill a company can get themselves into, as long as they spend enough on marketing they can work their way out of it on top.
I'm a libertarian who supports Damore in sprirt, but I don't love this lawsuit for the reasons given in the grandparent post.