Firing & hiring back employees policy?

My dad was physically assaulted at work and had to spend a night in the hospital for observation due to his injury. The man who assaulted my dad was fired. But because the union was going to sue the company for not hiring back employees who were fired, the company hired the man back at a different location. Is... show more My dad was physically assaulted at work and had to spend a night in the hospital for observation due to his injury. The man who assaulted my dad was fired. But because the union was going to sue the company for not hiring back employees who were fired, the company hired the man back at a different location.

Is it legal for the company to do this? If my dad sues, does he have a strong case?
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