You can’t just restrict changes like that though because the whole point of it according to Blizzard is to control busy areas so starting zones, popular areas, or wpvp will be switching regardless. If you are jumping between friends or guildies and can’t join them until you go to a rested area this is going to cause extreme confusion and hassle. As I said before just drop layering at that point as that’s where the problem lies. WoW was fine before layering and it doesn’t need it.