Earlier quoted context omitted.
This is a good point. Since employees are not shareholders they have no standing to criticize a CEO. Only someone with a financial stake in the future of a company should be able to voice their concerns without fear of retribution
Employees are financially dependant on the company for salary and perhaps stock options - surely that counts as "a financial stake".
This equity stake gives you a vote for which you can use to influence the actions of the board and thus the CEO.
Being financially dependent on the company to provide employment by no means gives you power over the CEO. Of course, criticism is not black and white - but being an asshole CEO is not illegal, and putting yourself out to "fight the good fight" sounds good on paper, but do you no good at all.