I don't see how this can be in question, if the employees chose their employer freely. How can one seriously oppose a corporate entity if one may not oppose the people who comprise the corporate entity.
"Corporations are people, my friend".
"Corporations are people, my friend".
If I apply to companies A and B, where A is ethical and B is unethical, but only B offers me a job, which I accept, have I freely chosen my employer? Let's assume these are the only companies available.