Claude Mauberret drops out…
This is one of my personal pet peeves. You hold elections for a reason. If you are going to require a simple majority (something I agree with) and you have a runoff to determine who of the top two will win, the person in 2nd place should not be able to withdraw from the race. If you do drop out, the next person in the race should be elevated to the runoff. Why? Because the person in the lead did not get a simple majority of the vote. So even though at this very moment more people voted against Erroll Williams than voted for him, Williams gets elected.
You cannot require the person in 2nd place to campaign. But there should still be a vote to determine who gets the actual majority.
Perhaps we should just rank candidates when we vote and solve the problem. This way, you know which of the top two candidates the voters like more.