Why will Arjuna be described in unkind words?

The 36th verse of chapter 2 of Bhagavad Gita for happiness continues with Krishna explaining Arjuna that he must fight this battle. He says that many of his opponents and enemies will describe Arjuna in very unkind words and mock him for backing out. Krishna was suppressed in the beginning by Arjuna’s grief. He says that such grievances are not suited for an Aryan like Arjuna.