You can't create closed source software for yourself - you have the source code, because you wrote it! But if you distribute that software to someone else, yes

You can't create closed source software for yourself - you have the source code, because you wrote it! But if you distribute that software to someone else, yes he holds that it is morally wrong to deprive them of certain rights, eg. the right to modify it for their own purposes. Given his apparent stance on non-Free software, I suspect he is not concerned if you choose not to write some. He certainly wouldn't have used it in the first place.