I would attempt to meet with civilian school if at all possible. Perhaps they do not understand that service academies do not offer appointments near as early in the calender year as civilian schools. If they do and they are pressuring you to make a decision, I think I'd accept. Then, upon receipt of a service academy appointment, you will have to decide what to do.......hang on to plan b until I-Day or release that scholarship, wrap yourself in bubble wrap and forge ahead with USXA.
All of this might hinge somewhat upon exactly what the conditions are that are attached to this scholarship. Do you have to sign something?