The analogy doesn't work too well, because employees of a company are distinct from its owners and decision makers. An employee in a private company is more akin to a civil service bureaucrat in a government, hired to perform some function. And we generally expect civil servants to be apolitical - they still get to vote etc, of course, but in their capacity as citizens, not government workers.

Mind you, I don't think that means that employees (or public workers, for that matter) should just shut up. But the argument for "should just leave" is stronger in this case than it is for citizens.