How does that help to punish thousands of students for a few illegal immigrants in their student body? Never forget that public schools are not companies, they are educational organizations. Unlike what you can do to punish, say, Walmart if you find illegal immigrants, you cannot punish a public university the same way. The admissions staff may be punished, the president or the provost may be punished, but not the whole university. Never punish people who have nothing to do with the crime, if you don't want to have marginalization in a region (this can be a whole country or a simple university).