You have a link to that claim?
Here is one article I have quickly on hand that references the fact that a student who is a Texas resident can be granted in-state tuition only if they are going through the United States citizenship process already.
From:
http://www.unionleader.com/article/20110724/NEWS0605/707249985
Excerpt:
In 2001, Perry signed into law the first state DREAM Act, which allows children of illegal immigrants to pay in-state tuition at state universities as long as they graduated from a Texas high school and are working toward attaining citizenship.
Here is also a link to the United States Citizenship and Immigration Services.
http://www.uscis.gov/portal/site/uscis
I hear that when all is said and done, it is approximately $30,000.00 a person to go through this process. My daughter has friends who are married and have gone through this process, and they had to dish out almost $60,000.00 for the two of them getting their citizenship, so I guess what I heard was at least fairly close.