because if the grid went down, these types of panels could keep feeding the house, out to the street, and electrocute a line worker

The inverter in these is designed to shut down if it doesn't detect a waveform from the grid to sync with - they are unable to create a 50 Hz AC wave on their own. As long as the hardware is legit (which is a big if with how easy it is to get unsafe junk in from China) there is no safety issue, it's purely regulatory.