The issue, to me, is that, while closing the door to Cubans, he keeps the door wide open for Mexicans and Muslims of varying origins.
If he had closed illegal immigration for everyone, that is one thing...
Say, isn't there a term for applying one set of standards to one group from a particular nation, religion, or ethnicity, but applying another set of standards to a group from another nation, religion, or ethnicity? 
I guess not enough Cubans vote Democrat....