I can't believe that they even asked you if Derrick wanted to work with that guy again or not. At a minimum, he should be fired because of what Derrick (and you) went through

I hope now that Derrick has already dealt with the incident report, he won't have to relive the experience anymore, and can heal

And I hope that the next person he gets is wonderful. He deserves that. And I don't want you to have to worry about anything like that happening again