This is very true--trying to create a single outcomes-based ideal of what's fair is both difficult and subject to the same strategizing that caused gerrymandering in the first place. Instead of choosing what "fair" is and maximizing it, the proposal takes a different approach: by using an extremely simple geometric rule, the algorithm seeks to avoid choices that would be susceptible to influence for political gain. Those are the choices that tend to result in gerrymandering, which by locking down power is expressly designed to be the opposite of fair to future voters. So instead of the difficult task of directly maximizing fairness, the proposal aims to minimize a great source of unfairness. I'd be curious to know how well it would work in practice.