Share the email from Rice with your GC and ask her to talk to admissions there, and get to the bottom of this. It is possible that you got an auto response to your question. No school “approves” of any student dropping courses for second term and it’s standard language that you were accepted based on your second term slated classes. There are kids who will drop to minimum or nothing, and high schools that permit it, and it is not encouraged. What actions are approved by a college and whether they have consequences for it are two different things. It’s not something they will approve of students doing. But rescinding is a serious, drastic action.