From what I understand, Glycol based fluid picks up it's moisture from the air. If Silicone based fluids don't absorb moisture, there shouldn't be any in the system? It's not like water is leaking in. Is my logic sound?
No, because there will always be condensation. The braking system is also not sealed as it has a vent in the cap. But even if it didn't, there would be condensation on the inside of the system, especially in the cast iron master cylinder and cast iron calipers and wheel cylinders.
