Some insight from the light novel about the old man who seems out of place in this chapter. The old man's son lived where the gate appeared. He donated alot of his money and savings for the S rank raids only to lose hope and become bitter at each failure. They probably shouldn't have shown him at all or shown us how important this raid is to Korea.
Oh yeh, completely forgot about that old man story, if we don't have more info about it at end of this arc in manga, maybe we should disclose it not in spoiler for manga only reader?