Why is it "bad" game design, like anything afoul of what kinda silliness is being implemented? You could actually do worse, he could have made them scum Lovers, for example.
Also, the flip doesn't explicitly out the other neighbor? Only if, say both were innocent teeth suckling Human/Machine town who casually admitted they're happy little neighbors and suddenly they get converted and set themselves up for failure. In this scenario it wouldn't be fair to them, but this is just one out of many. And basically requires assuming Polar didn't actually know what he was doing anyway, so there's genuine human error to account for as well