Hmm-m-m. I think you're making what is known as a Bare Assertion Fallacy . With a touch of red herring thrown in for seasoning. I said nothing about illusion.
What I said was that I suspect that free will is a perception that we have. I think an omniscient objective observer would think we have free will like an amoeba, for example, has free will. The amoeba has physical constituents which are determined completely by the laws of physics, it reacts according to environmental factors which are determined completely by the laws of physics, according to it's biomechanical reactions, which, again, are determined completely by the laws of physics. And yet it wanders apparently sometimes randomly, sometimes purposefully. Is that free will?
Now, for a human, maybe we have some magic thing, let's call it a soul, which makes our reactions somehow not governed by our makeup, our environment, and our history. But nobody has observed or measured one of those yet. Yet, many people say it is obvious that we have one of these. I don't think that is a scientific or thoughtful conclusion. And so it is for the notion of free will, for me. I realize that many will disagree.
There is no imaginable mechanism by which that could have happened, so the claim is (of course) arbitrary, and should simply be disregarded.
Show me a mechanism by which free will can exist, and I will readily concede the point. It's reasonably well accepted in the scientific community that everything we do is governed by the neurons in our brain (mediated by the rest of the body, no doubt). If that is true, and absent an observable soul, it seems simply that there is no imaginable mechanism by which free will can exist. Therefore, as someone recently said this notion should just be disregarded. ;-)