I don't see that it proves anything like that at all. Being able to detect that the mind has come to a decision before there is any physical expression of it says nothing about whether that decision was pre-ordained before the big bang or even whether it was arrived at based solely on the sum of the history of all external stimuli.I was surprised; but not because of what the experiment showed, which I already suspected for years. It was because I was only looking for proof that our subconscious was aware of our decisions before our conscious -which I had read elsewhere-; so I was surprised to find everything I was trying to prove in one single source.
I see a huge problem with the conclusion that they can tell that a decision was made seven seconds before the person was aware of the decision -- and I didn't see any claim that they could tell what that decision was.
Consider a button sitting in front of you and you are told to press it with your right hand or your left hand and then to repeat that at a steady pace, each time picking which hand you are going to use. In seven seconds, at even a modest past, you can press the button thirty or more times. Are they really going to claim that the decision on which button I am going to press thirty times from now was made before I pressed the first button?
Or imagine that you are presented with between two and ten buttons, say on a touch screen display, and you have to decide which button to press based on which one you think is "prettiest". The buttons appear in all kinds of random patterns and positions. Some times they are all just different colored circles. Sometimes they are various shapes. Sometimes they are images of buildings, animals, people, landscapes. These might all be mixed up in a single iteration of the test. Is it safe to say that you can't make a decision about which one to press until they appear on the screen? Is it safe to say that you make a decision before you press a button? Now, is it safe to say that it is seldom going to take you much more than one or two seconds to press a button after they appear on the screen?