Other news websites have reported it accurately:
Musk’s most recent grievance stems from the fact that his factory is located in a part of California that has stricter rules for reopening than the rest of the state. On 7 May, governor Gavin Newsom announced rules to allow some manufacturers to reopen on 8 May. However, the statewide rules do not supersede local restrictions, if they are stricter, and many of the state’s most populous counties, including seven counties in the San Francisco Bay area, have decided to keep in place their more stringent rules through the end of May - The Guardian
The restart defied orders from the Alameda County Public Health Department, which has deemed the factory a non-essential business that can’t open under virus restrictions. - news.com.au
Tesla restarting Fremont factory despite county orders, coronavirus threat - sfchronicle.com
Also, we have the statement from the Alameda County Public Health Department
It was a county order, not a state order, as Elon Musk said:
Don’t mislead the public. State said YES, an unelected county official is the problem. Tesla factory in adjacent San Joaquin county is fully operational.
BBC News also correctly reporting it is a county restriction.