This has some points...
1. It creates a loop.
No it doesn't. If the researches have time to tell the person making the decision what decision they will make, they also have time to observe the results of telling the decision maker the new information.
If you observe yourself taking a decision that you have no choice taking, you can also change it.... which means you then have a choice....
Indeed I can at a high level. And if I change my mind as a result, that process is also deterministic.
It also shows that 'we' can be independent of ourselves and observe ourselves taking decisions (predetermined or otherwise). This is the 'observer' that many spiritual people talk about. You are getting there!
That supposes that there is a higher level observer to do the observing. This is false. The observer is the same entity as the observed and that creates complex and hard to predict feedback loops, but there is no need to suppose that these are not deterministic.