Nothing about that has anything to do with whether something he said was insightful or not. It’s possible for evil people to say smart things and for good people to say bullshit things.
Rumsfeld said a smart-sounding thing he got from somewhere else, but it was just a lie. He knew the WMD claim was made up because he helped manufacture it. Iraq's non-involvement in 9/11 and our inability to accomplish regime change were "known knowns" prior to the invasion.