What wouldn’t count as working conditions under such a broad standard? Could I circulate an open letter demanding that I get a tech lead position instead of my rival because I don’t think people will enjoy working on their team? Could a salesperson circulate an open letter demanding that you should be punished because your bad engineering cost the company a big contract?
What I'm saying is that I think the open letter's attack on Musk was also a simple personal grievance. The signatories don't like Musk, they're distracted and embarrassed by his Tweets, so they demand that the company denounce him. (The letter said more than that, but if broader systemic reforms were their primary goal, why include an inflammatory attack on one specific executive?)
The courts have covered this. Generally, individual grievances are not protected. Whistleblowing may not be protected. Egregious or offensive language or coerced speech is not protected. Language that is disparaging without being an attempt to improve conditions is not protected.
