Because he’s right:

A speech last week in which Rumsfeld likened critics of the Bush administration’s war strategy to those who tried to appease the Nazis in the 1930s prompted many Democrats to call for his resignation and boosted support for a congressional resolution expressing no confidence in him. Rumsfeld later said his remarks were misrepresented and that he was cautioning against a repeat of errors made in the past, not accusing the administration’s critics of trying to appease the terrorists.