Nearly a quarter century ago, wise philosopher Jeff Goldblum, aka Ian Malcolm, spoke some of the most impactful words spoken on the silver screen:
The two part episode that takes us back to the home of a species thought extinct (much like the dinosaurs of the Jurassic Park realm). Geonosis is barren, left to waste away after its usefulness has been sucked dry. Or so it is thought.
A Geonosian has survived. Somehow, life found a way. Not just the life of the Geonosians, but the life of the Seperstists. The life of The Clone War. The life, and heartbeat, of rebellion.
It is often forgotten that the Seperatists were rebels. Even though there tactics may not have been ideal and there beliefs may not be what we agree with, it does not change that they were rebelling against the ruling power (or so they thought).
While it was believed their fire had been stomped out, their heart still beats. What, you ask, is there heart? Battle droids. They were the gears that kept the Seperatists going and allowed them to pursue what they desired to pursue. In much the same way the stormtroopers would for the the Empire, the battle droids sheer number were the power of the Seperatists.
If the droids were the heart, then the Geonosian people were something on a more cellular level. Building the battle droids, working on the Death Star, and creating a home for both Seperatists and Imperial forces, Geonosians were what allowed both powers to rise, at least in some way.
Such a resourceful and creative species is not easily destroyed, and we see that as the rebels find Click-Clack. Notice at the moment that it seems the rebels are about to kill him, the droids (heart) stop working (beating). All life force is focused on keeping the last Seperatist, and the last of a species alive.
Let us pause for a moment and talk about Saw Gerrera. Somehow, through decades of war, Saw still stands. But not without scars, because life leaves scars. He still has found a way to survive because he is a vital aspect of the Rebellion, as he was one of the first true rebels. That is, he was part of a group of rebels who was truly fighting in a guerrilla way with guerrilla tactics like the infantile Rebellion later would; had he not survived, it is a wonder whether the Rebellion would have survived. The life of Rebellion found a way.
Just like Saw is, presumably, the last of the Onderoneon rebels, Click-Clack is the last of the Geonosians, save for the queen egg he carries in hopes of recreating the life of Geonosis. Maybe it is that part of Gerrera, the part who had lost so much and had to keep fighting, the part that lost his sister and his people but realized that life must go on, that allows him to let the last of the Geonosians go in order to rebuild there people.
Life finds a way.