It isn't even optional. Anything with a motor should have sufficient executive authority on board to decide on how to safely power down in case of trouble. Loss of communications is a major impediment to deploying robotics to the point that I think it should be outlawed to have robots that do not have all of their thinking done locally.

But I suspect that this will be one of those regulations written in blood.

At the bare minimum there should be a local independent system that safely shuts down the robot if it doesn’t get heartbeats from their control network