What does a destructible level have to do with keeping all RFC calls?
When you destroy something via TNManager.Destroy, all of its RFCs go away too, and if you dynamically created this object, the "create" call also goes away -- so new players will never even know that the object existed in the first place.
Instead of sending messages that destroy regions, use TNManager.Destroy. Keeping a stack of RFCs instead of only the latest is a very strange thing to do. Think about it... player move updates, sent say... 10 times per second for 10 minutes -- that's 10*60*10 = 6000 RFC calls in a stack that must be sent to all new players. Why do that, if only the very last update actually matters? The fact that Unity's built-in networking does it shows just how little they thought things through in a real-world scenario.