The runoff voting downside is incorrect, the "drag the voters up to yellow and watch how it makes red win" example. This is not "see how making yellow more popular makes yellow lose". It's actually "see how making red more popular than yellow makes red win". The movement of the voters is not for yellow, but for red and yellow in a way that gives more voters to red.

There is no way for yellow to be the only candidate to get a boost of voters in the demo. If there were, it would only demonstrate further that yellow would still continue to win.

Runoff voting is the way.