The rationale behind this statement is that unions would only arise in response to unfair practices on the part of management. Unions tend to arise because workers feel that they are not being treated well by the firm. They may feel their working conditions are too hard or that their pay is too low. They may have low morale. The statement given assumes that such issues are the fault of management. It implies that good management would treat workers in such a way that they would not want to unionize. Therefore (this statement implies), any firm that gets unionized must deserve it for having bad management and having a union (to fight unfair practices) for management would prove this.