Unconvincing examples, because those are simply personal grievances and unrelated to broader company culture.

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.