A few thoughts here:
First, although the Governor's order referenced and incorporated the Federal exemption, I don't believe the municipality's order, which preceded the State order, specifically recognized it. There is of course the question of whether a State order preempts a local order, but there you have it.
Second, assuming Tesla is covered by the State's application of the Federal exemption, they would be an outlier when all of the other auto mfrs have shut down their assembly plants because of pressure from the UAW. The union had been complaining that if the workplace was too dangerous for white collar office workers who were sent home to telecommute, then why were factory workers being treated like second class citizens. When the Big Three folded, with foreign brands quickly following suit, it was a major victory for a union that had been losing members. As the virus spreads, if Tesla forced its non-union workers to continue working, their fear and unhappiness could prime them for the UAW to initiate a successful recruitment drive: "Only we can protect you Tesla workers from a greedy corporation."
Third, imagine if Tesla's factory suffered a virus outbreak affecting multiple workers, causing sickness and even death. Tesla would be vilified by the press, the local community, and the UAW, as the only car mfr that had not shut down. Before you could spell "class action lawsuit", the plaintiff's bar would mobilize into action, saying "If only Tesla had done the responsible thing and followed the rest of the auto industry, they could have avoided the harm to its workers." The negative publicity would damage the company's reputation, the potential liability would affect its share price, and once again expose Tesla to the risk of a union recruitment drive.
So Tesla is in a very sticky situation. Keep the plants open, and there's union and litigation risk. Close the plants, and depending on the length of the closure, it places the company's existence at risk, never mind the drop in share prices that would precede it.
