If he does, He can go to the soc terminal and make himself unelectable. From this point there is 24 hours to vote in another leader. It doesnt matter if only 2 people vote for the new leader, It doesnt have to be the majority of the soc - as long as the old leader is unelectable and the new leader is.
If the only leader doesnt want this or isnt online, then you will need a majority vote. Same idea, potential new leader marks himself as electable, and the others vote him in. It takes 24 hours to change.