Is In-state tuition for illegals illegal?

A Kansas law allowing "undocumented immigrants" to pay in-state tuition has been challenged by out-of-state students and their parents:

Kris Kobach, who is representing 24 out-of-state university students and their parents, contends that a 1996 federal law prevents the state from offering to undocumented immigrants residency-based benefits that are not available to all U.S. citizens.

There are some side issues, like whether or not the students have standing, so there might not be a ruling on the merits.

The article notes that 30 students in Kansas took advantage of the law this year. I can't understand this. There is apparently no concern about the law that has been broken here. One of the chants from the ID and Amnesty for Illegals rally Malkin blogged about was "Democrats you have no spine, we'll pay you back election time". Excuse me? Non-citizens, documented or otherwise, should not be talking about "election time". They (theoretically) can't vote. Update: Or as Ace puts it:

Memo To Karl Rove: Illegal Aliens Aren't Supposed To Vote, And They're Not Going To Vote For You Anyway. On the other hand, there are millions of Americans (in both parties, and in no party at all) who are fed up with this country's refusal to enforce its immigration laws, and they do vote.

It seems being "undocumented" is rapidly becoming a protected minority status. The handing out of driver's licenses, the lack of control over who votes, and a near total lack of penalties for being "undocumented", is starting to make citizenship look like all responsibility and no rights.