Which means that it’s not actually a backup, because if there’s some sort of electrical short that causes the connection to fail, that plane will crash.

Autopilot systems are routinely used today, so that pilots don’t have to have hands on the control for the entire flight. In any situation, or during takeoff/landing, the pilots take over for the autopilot. Outsourcing the pilots to a remote connection means that you’re outsourcing the backup, not the primary.

So you’re either swapping the autopilot to the role of backup (which is already a no-go in the current aircraft setup, so there’s no reason to assume they’d suddenly be okay with it) or you’re relying on the remote pilots to be as reliable as a pilot physically in the plane, which is foolish.