Was excited for a minute because of the plural, OP. But if it really was one frustrated guy acting in a spontaneous individualist fashion, it doesn't mean shit.
It's true that a small dedicated minority can totally fuck up a company from the inside. For instance, strikes at Amazon usually work like this: People just leave the building for some time, and at first this is highly stressful for management, but over time they figure out who takes part in strikes usually and they take care to show more people how to do this or task and they adapt. In Poland, there was a strike with people inside the building putting one item in a tote or on a cart and then "closing" the tote or cart. There are lots of processes inside Amazon that work with the assumption that one person fills up a cart or a tote with lots of items, and when it's full, the tote or cart gets "closed" with the scanning device you have in your hand, and then the cart or tote gets taken by somebody else in another step (putting the stuff on shelves or putting it in packages). If we lived in the pre-computer age, the people not participating in this strike would just put more stuff in the totes or on the carts. But the activities have to be synchronized with the database representation now, and the system has no way of letting normal workers "open" again the carts or totes. (Which is not to say that the re-open feature doesn't exist, there are people in special positions who can do that, but to unlock that for everybody would fuck with tracking individual activity.)
Dunno. The criminal in this email could be completely made up by Musk (a preemptive strategy to get loyal workers more alert in case something like the story is about to happen for real), but what he describes strikes me as true either way. Some people want to see Tesla fail. You can bet on a firm going down on the stock market. Maybe you have heard of a recent case in Germany, where somebody tried to kill or maim a soccer team with bombs? That soccer team is also on the stock market.