let's do the seal team six hypo. president orders st6 to assassinate a political rival bc rival is a threat to national security. possible this is absolutely immune under pres's commander in chief power. if it's not, then it gets presumptive immunity (which may be absolute anyway)
president goes to olc, which has now been stacked with "yes this is official act" lawyers such as john yoo types. "please stamp this order to assassinate my political rival an official act." "official act boss!"
president: "i was told this was an official act before i did it."