There are a number of ways in which we can justify the idea of bringing this work back to the United States. Let us look at a few of them.
First, we can say that this move will definitely result in better workplace safety and general working conditions for those who are doing the work. We generally do not think that it is acceptable to exploit children, even if working long hours is preferable to the alternatives that they have. By bringing the work back to the United States, the company will be making its products in a way that does not harm or endanger its workforce.
Second, we can say that this move will be more ethical. If the firm stays in Bangladesh, it will be making a profit off of the exploitation of the workers in Bangladesh. Its profits will, in a sense, be tainted by the fact that they were obtained by using workers who are working in conditions that we would never allow in the US.
Finally, we can justify it by saying that it is beneficial to the United States. People in the United States need jobs just as much as people in Bangladesh do. It is just as important to create jobs for Americans with lesser educational levels as it is to provide them for people in Bangladesh. Thus, bringing the jobs back to the US is an action that will help people and is therefore justifiable.