Oh, I definitely don't think this was made with anti-immigrant sentiments in mind. However, it's unfortunate that we cannot have Superman depicted as a shining beacon of the American dream on the big screen right now. So a twisted version that exploits the fear of the other and the fear of the unknown 'alien' may unwittingly contribute to validating peoples' prejudices.
Also, I hope this doesn't damage Superman's image or the way people perceive him in any way. Especially since there isn't the specificity of this being a DC 'Elseworld' or AU like Red Son where people clearly know it is a deliberately twisted take on the character. Not an ambiguous "This is how the character may realistically be like" message coming from a rival studio movie like this one.