Consciousness is not found in the brain.
Backing up the brain is like building a copy of your car to see how you used to drive. The driver is what is important, not the vehicle.

So, here we have a group just wanting to kill people.
Probably for organ harvesting.

Further, the chemical storage medium used by the brain is much denser storage medium than anything digital we use, so the "preservations" will be quite large, and prone to defects.