Had they limited their critique to channels outside the Tesla family of affiliated companies what they had to say might be OK — depends upon employment policies about doing/saying something that criticizes the companies.
That they did it on internal networks is indicative of total idiocy. These are the types who will sabotage.
Fire them immediately with no severance, no medical benefits, no reference and anything else that can be done to mark them as unemployable by any other company.
Stupid should hurt.
You're a nicer man than I.
I'd give them glowing recommendations to my competitors...
Tesla and Spacex are separate and not affiliated with each other, except starship might use tesla batteries packs for internal stuff