Subject matter expert on rescuing people in exigent circumstances, here. Yes, it's dumb to travel towards Florence.
It's a huge, unpredictable, and life threatening storm. I'm in Charleston, pre-staged for emergency response. I'm in twice daily conference with the weather wonks. There's currently no other weather forces steering Florence, and the National Weather Service doesn't really know where the storm track will go. The hurricane hunters have stopped flying Florence, because it's such a wildcard.
If you decide to go, despite it being truly dumb, you need a very robust risk management system in place. Bail out points and routes identified, with pre-agreed parameters that trigger turning around without further debate or argument. Take all emotions out of the decisions, from the moment you buckle your seatbelt.
Also, be aware that mandatory evacuation means government services are withdrawn. If you get into trouble, 911 will be very sad for you, but there is a real potential they won't have any resources available to help you.
edit: spelling