AT UIUC CS engineering has been one the hardest to get into in the last few years and many with high stats (including many non-Asians and many in-state) get rejected for it (as many have reported, they have been rejected for CS engineering at UIUC but accepted elsewhere such as Michigan). Did you list a second choice major in your application? If so what was that? If you listed a second choice major and got rejected for CS, they would have considered you for second choice, and then if rejected from that second choice they would have considered you for undeclared major in the Dvision of General Studies. If you did not list a second choice major, then if rejected for CS, you do not get considered for any other majors and thus are rejected based only on the CS decision.