This assumes that everything an AI (or more likely an evil _user_ of AI) can do requires its active participation on D-day. Creating a virus that spreads like C

This assumes that everything an AI (or more likely an evil _user_ of AI) can do requires its active participation on D-day. Creating a virus that spreads like Covid but kills like Ebola would be complete as an AI use case long before the first person sneezed. Even if the doomsday case were active the danger of this tool increases in proportion to its usefulness. By the time AI is so powerful that we need to "turn it off", there will probably be society-level negative consequences for doing so.