Taking this one step further, auto repair businesses can't very well repair cars if there are no parts available, and those parts come from Fremont. Therefore, the Tesla factory would (at least in part) theoretically already qualify for an exemption under the existing order.
One could also make the argument that (given that private transportation has been deemed an "essential" service) replacing worn out or destroyed cars is essential, and thus manufacturing finished cars qualifies for an exemption.