My argument would go something like this: If you are the computer, then it is free will. If you could predict the computer, you could argue, but you can’t. You can’t even do this theoretically since you’d need more mass than the universe and can’t initialize your predictive model. So you can only say “that decision was made inside that brain”. That is at least one sensible definition of free will.
It’s like looking at a motor that breaks down and then saying that it’s not really the motor that breaks because the motor had no choice in it’s parts breaking. That’s just rhetoric.
The error I believe is that we don’t want to accept that sentience can arise from mechanical universe and it’s a matter of degree and that this can create meaning. People want to set the bar higher because they want the idea of some type of “pure mind”. But since we’re already discussing the meaning of all these things, arguing that what you are reading is just quantum physics is rhetoric.
Either what you are saying is supposed to be meaningful, or you concede that your words are meaningless. Then I anyone else wins the argument by default ;)
Basically the definition of free will can only be made by someone who claims that meaning exists, emerging from the material world. Therefor within that emergent layer of mind and meaning, a definition of free will other than basic physics is at least acceptable.