Several thoughts.
1: Did Paroh kill any jews personally? Haman?
2: Is hitler y”sh evil because he killed jews or because he preached a certain hatred towards jews?
3: Would hitler y”sh be any less an evil person if the german population resisted him?
4: Harbei shluchim lamakom. He didnt have to volunteer for the job (the Rambam says something very similar regarding mitrayim).