"A video game based on a current war is.. makes any sense at all. It's disrespectful."
But before, you said WW2 doesn't matter anymore, the families of the soldiers who died no longer care about their lost loved ones, and then you go on to say this. You're the one being disrespectful here, lady.
After listening to her saying that, I don't think any of her opinions hold water.
As for the Mature rating dispute, it's up to the parents. If your child is mature enough to handle it? Go for it. If they aren't? Don't.
Simple as that.