As a counterexample, I click that feedback all the time and nothing ever changes afterward.
Using feedback on your sessions makes that session, and presumably all attached data, fair game for training.
They explicitly ask, after the rating, whether they can look at your chat. You can just say "no" to that, if you believe that they are following the rules they say they are.
Your original statement of "using feedback gives them permission to train" is just plain false.