Ex-Presidents have the right to be assholes.
Ex-presidents do not have a right to immunity from criticism.
So far no one’s mentioned the hateful Jimmah Carter, who has been a one-man wrecking ball against U.S. foreign policy since being kicked out of the WH in 1981.
Trump should send out a truth squad to dog Obama’s steps wherever he goes and issue press releases on the heels of every speech he makes, and contradict everything he says.