Sorry, I don't know, but there were so few times that IllumiNations was that late in the evening that it is possible no one reading this thread has seen it at 10:30 from R&C.
We often do late dinners in Epcot so by the time we're finishing the servers are setting up for the next day, but we have never been asked to leave. Currently, the dining reservation page shows R&C's dinner hours as 4:00 to 8:30 in late December. Just a guess, but if you are seated on the patio, I don't think they would ask you to leave and if you are seated inside you can probably wait in the viewing area adjacent to the patio.