Ok, that's what war is, and I don't doubt that Superman would realize that. But when Wonder Woman is involved, Superman should expect her to have standards, at least. At the very minimum, that standard would be trying to prevent atrocities from happening and not helping to celebrate them.
I think she's incredibly out of character here. Maybe forgiveness is out of the question here, but I don't see her as advocating vengeance. I'm not sure how this story fits in the the DC universe, but if Eisenhower is president, wouldn't this be a little more than ten years (comic time) after she decided to reform a nazi agent rather than punishing her?