How does the disappearance in Chapter 25 make the Memory Police officers' jobs easier, as discussed in Chapter 26?

Once everyone's left legs have been disappeared, the Memory Police have a much easier time rooting out those individuals who are immune to the disappearances. The narrator points out that no matter how hard someone tries to fake not having a left leg, they cannot use the same cadence and rhythm of everyone else as they hobble around trying to keep their missing limb as much out of the way as possible. Thus, the people who are enemies of the state because they are able to operate outside of the state's control are captured at an even more rapid rate after the first body part disappearance.