McCabe will not be long as the acting head of the FBI.   He was the one in charge of the FBI  investigation of Hillary's email fiasco.  His wife, Jill, received $700,000 in her failed bid for a senate position in the last election from Terry McAuliff, a big
shot with the Democratic party  and  long time supporter of Bill and Hillary Clinton. When his wife's connection to the Clinton's came to light, there were calls for McCabe to recuse himself from the investigation but he would not do so.
He was also appointed to being the Deputy Director by Comey in 2016.  If the goal is to remove politics from the FBI and to restore its now tarnished reputation, McCabe needs to join Comey so he can spend more time with is family.