1. If a Park is at a Stage 4 closing nobody is allowed in. Effectively, nobody has a valid ticket for entry to the Park in this situation.
2. If you make any reservation for dining inside a Park you are warned that you must have valid Park Admission. This warning is given verbally if you make a phone reservation, or is on you confirmation if done online.
3. As stated in #1 above during a Stage 4 Closing nobody has valid Park Admission. As stated in #2 above, you must have valid Park admission to dine. So if you are not in the park at the time of a Stage 4 Closing and you do not make it to the restaurant, you are at fault for not having valid Park Admission to miss your reservation.