Not much, I'm afraid. Stone was highly loyal to him, doubtless working with him since before all of this. He was allowed to keep his mind.

[Stone as a person is not exactly the interesting part to Turo, though.]

But...Infinite said that he has not seen him for some time now. He also said that the doctor has changed. When he first met him, he was excited and talkative, but he seems like a different person now. Colder and more controlling - more obsessed with the concept of removing free will. Of course I do not know what might have happened with Stone, but I have difficulty believing that the two changes are unrelated.