It's like burning down your house to help warm up people caught out in the cold. You're going to inject thousands of people that do not speak your language, many of whom are not literate in their native language, most of whom are not highly educated, and will require significant government assistance to make ends meet..and somehow this is going to help the Detroit economy or the existing citizens of Detroit?
There are reasons to support refugee acceptance based on sympathy or compassion, but to suggest a net positive to the economy by an influx of third world peoples is asinine.
Why in the world would you not help the previously existing citizens of Detroit and employ them rather than bringing in refugees (or like they see in Europe, often economic migrants mixed in with refugees)?