Probably due to the Easter Holidays. The courts are probably going to take some time off and they would want to have an answer before then. Or they could just be wanting to come down hard on 0 and show they are in charge, not him. It will be interesting to see if he just ignores the court or not. He is elected, after all. (That last comment was meant as sarcasm.)
it is not at all uncommon during oral argument for the judges to give you a short turnaround time to address, in writing, an issue that comes up during argument that was not presented in the briefs prior. what is uncommon is that here the subject matter was the President’s ill-considered remarks that she may or may not have even known about!