Why does Krishna say that the Kauravs are already dead? || Acharya Prashant, on Bhagavad Gita (2020)

Questioner (Q): On seeing the divine form, instead of feeling gratitude towards the Lord, why is Arjuna more fearful, and says that he doesn't find any peace in the four quarters, and asks the Lord to have mercy upon him?

Also, Arjuna sees that all the sons of Dhritarashtra with hosts of monarchs etc., enter into the Lord’s mouth, and Shri Krishna at one place says that he has already slain all of them. Does this mean that everything is preordained in some sense? Why is he predicting the future?

Acharya Prashant (AP): No, look at the ground reality, the practical situation. Arjuna has just been delivered a shock. It's a rude jolt—why would he feel grateful? His friend of 40 or 45 years, the one he thinks as intimately as the back of his hand, has suddenly displayed a totally unseen form to him. Why would Arjuna feel grateful? And the form is not pleasant to top it; the form is unnerving, violent. So, Arjuna is disturbed, and he says, “You return to your chaturbhuja-rūpa. That is far better, far more pleasant.”