Well, given the MC went to save the village in the first place, but then Granpa Elf was killed with prejudice by the Saint's cards, assumed to be part of the enemy instead of checking if they were allies, only too late. This put a big damper to the MC's strategy to save as many innocents as possible, before the Soul Eater orc could become too powerful to beat. That created a situation which demanded more time to set up a new strategy given the rules of that world, which unfortunately increased the collateral damage and more dead innocents.
Given all that, I would be pretty bitchy as well, especially ruthless to the Saint who has the biggest part of responsibility of an horrible situation that could have been prevented.
I'll give that she's portrayed in a very uncaring light in this chapter when she showed some giddiness for the cards she could get. Unless there's a bigger picture...