As I understand this question, you are asking why it is both good and bad for business to have labor unions pushing for workers’ rights at the same time that you have management and ownership pushing for profits. I will base my answer on this idea.
It can be destructive to have both these sides pushing for their respective goals because it brings the two into tension with one another. It creates firms in which the management and the employees are not working together. When we have different goals within the firm, we end up with distrust and animosity because each side thinks that the other is trying to harm it.
On the other hand, it can be good for the business to have both of these sides represented. It is, of course, necessary for the business to push for profits or else it could never stay afloat. However, the presence of unions can actually make its workforce stronger and more productive. It is possible that workers will feel more empowered if they have a union. This can improve their morale and their motivation to work. When workers feel more motivated, they can be more productive and can help the firm.
Thus, it can be both good and bad to have labor unions and management working towards different goals in a given firm.