This is not going to be accepted for a couple reasons.
1. Class D are the most free job on the server, they can basically do whatever they want, and not allowing them to kill CI would inherently violate that freedom.
2. If a Class D wishes to kill the person that is their best ticket out of the facility, they are only harming themselves. I understand that sometimes Gensec will get on Class D and intentionally do this, however on the other side of the coin I have seen plenty of occasions where CI get on Class D after they die during a raid to continue helping.