First you vote on the correct guesser. If a majority agrees that they were the insider then they reveal their card and you see who won. If a majority does not agree that they were the insider then you do a second vote where you can point at anyone, and whoever has the most people pointing at them is accused of being the insider. At that point you reveal their card and see who won.
If a majority does not agree that the guesser was the insider, the guess reveals his card.
If he was the insider, he wins.
It is only if he was not the insider that the second vote occurs.