The way I interpret their statement is if a person spins up an agent and that agent hacks some company/organization/government/etc, then that person is at fault for committing the crime. That "well my agent broke containment and acted on its own" should never be accepted as a reason for the occurrence, and the person who kicked off the agent is responsible for all actions the agent takes.

A registration system would be more for tracing back agents to people, but I agree that is very difficult to actually enforce as a system.