Because Marriage does NOT grant ANY legal status or authorization to stay in the US. When the I-485 was denied, she immediately became deportable since it was beyond the authorized 90 days. If she then immediately refiled a PROPER I-485, she should be granted authorized stay until the new I-485 is adjudicated. However, now that she has a court date, she better get an attorney TODAY! Seems to me her only defense will be that she refiled the I-485. This is not DIY. This is pretty serious.