Unfortunately, that’s become a rather loaded question. I’m not going to add anything to my original post to explain my view of UG any further, for two reasons. First, I don’t have a good sense of what common ground we share so any attempt to further explain my view of UG would likely require me to make some false assumptions about what knowledge and beliefs we share. Second, there are far better sources. Norbert Hornstein, a philosopher-turned-linguist runs a blog that covers all sorts of things related to Generative syntax and beyond. As of this post, the latest posts on the blog are addressing the SA article that my post addresses and Tom Wolfe’s latest book. A word of warning, the tone veers toward the polemical pretty often, and some of the posts are about theory-internal technical debates. Obviously, you can always read some of Chomsky’s writings. I’m sure regardless of your background, you could find an essay of his that’s pitched toward you (he’s got a lot of writing). Or, even better, email Chomsky directly. His address is listed, and he does respond.
What critics of UG seem (to me) to mean when they say “Universal Grammar” varies depending on the critic. Often it seems to mean Chomsky (or Pinker), or it means rationalist epistemology, but recently I’m starting to see it as a term for Chomsky’s suggestion that the human language faculty can studied as a natural object. But that might just be me.