If a Bronze got to Challenger by... [Hypothetical Question]

After thinking about how unfair Riot is by making a player play the rest of a 4v5 game, I thought of this question: If a Bronze gets to Challenger in a month because ALL his games that he played in to get to Challenger had an afk on the enemy team, what would Riot do about it?

Would they demote him? Punish him (For "abusing" afks)?

Now, if he played legitimately, he would drop very quickly of course. However, lets assume there just kept being afks on the other team, until he got to the number 1 spot, and yet he keeps his number 1 spot because of afks (yes, i know almost no one would afk that high up but lets assume otherwise for the sake of the question).

Leading back to my question, what would Riot do about it?

Would they finally implement a better afk system that actually works and is fair to both sides in the event of an afk instead of punishing the afk and moving on? Is this what it would take? What would they do? I would like to know what you guys think. Please remember that this is a hypothetical question.

EDIT: Deleted old thread and posted this one for the sake of a poll.