The MC in the first day would understandably be like this as it's a zombie apocalypse, but 5 days later trapped at the school and the author has not given a hint at him being a survivor outside of hiding with no plans. These two girls are understabily intimidating, but it's very important to actually hint at the MC having a damn spine, especially due to what type of person he is. I really hope the author shows the MC's potential, otherwise, the focus should have been these two school girls.
I'm already thinking that would have been the better decision.