I think you've missed the boat here Aaron;
We get why you're saying that fourth and fifth should have a "vote-off";
But the problem is that it's redundant; it just increases the length of the competition for no apparent reason.
Because we could (and as Rukoh and others have pointed out) should just take the top 4 and move into the next round, without a need for a tie-breaker of sorts. Why? Because whoever places 4th (minus the event of an actual tie between 4th and 5th, of course) will have already garnered more votes from the public, in a vote where people could vote for both, either, or neither. Point is, in a poll with pretty much unlimited choice, 4th will be above 5th. You know, hence the ordinal ranking!
In most competitions (well, not official ones with caps) but ones where you get an odd number of people and you want to head to head styles to go through the usual 32-16-8-4-2-1 style; people just find a stage to cut off at. We had 9 participants, and now we are at 5? Instead of adding an extra stage, we could just do the following:
1) Stage one - X participants - Y go through because of a draw
2) Stage Two (should be unaffected by the draw in stage one, really) - out of those remaining Y, just take Z [an even number] to go through and the rest are eliminated.
3) Stage Three - If you wanted to add another stage, could do 2 top going through from the top 4,
4) Stage 4 - Final stage.
However, adding in the extra stage after 2 is just unnecessary. Taking the top 4 will streamline the competition and not breach any issues of fairness.