Oktas 8>
I dont think its a racism issue you are looking at there. Sure, we train people from all over the world; they have student visas.
To give them a job they need a work visa. Not easy to get in an industry where we have a surplus of low hour pilots.
Having said this I know of one of the above schools that has hired a few instructors that had trained after moving here from overseas. Not sure what grounds they got their visas on, but I would guess that it would be on language/cultural skills rather than the merits of their C-cat instructor rating.