I think the concern is that if your employer, whether it's a public sector employer or a private sector employer—i.e., the institution that puts food on the table for your family—indicates firmly to you that it has a preference as to how you're going to vote on the question of unionization, that becomes a very difficult choice for an employee, because the day after the vote, your employer, and again, whether it's the public or the private sector, is still your employer.
On April 19th, 2016. See this statement in context.