There are a number of blacks who view Hispanic immigrants as competition for jobs and are not turned off by Trump's immigration stances. More than some folks think.
You are absolutely correct many Blacks are not turned off by his immigration stance. Rather they are turned off by his racism. It's possible to want to shut down illegal immigration without being a racist asshole like Trump. If you Republicans did that maybe you would have a chance. As a legal immigrant whose parents went through the process (I was a kid) I don't carry any water for illegals. But when you people start demonizing these people unfairly, you bet I'll come to their defense. Don't unfairly demonize people. It might not be good politics in the primary but it is in the general. Moreover, and most importantly, it's what a decent person would do.