The main purpose of exposing the SOA feature in the UI was to allow changing of the other values for registries which required them to be within specific boundaries.
You're right the system should not enforce the nameserver being within the same zone and it should default to the first nameserver belonging to the master organisation or reseller. This is coming in the 11.0.0
update.
deydod
There have been some efficiency improvements as well as a fix for errors being logged on orchd startup when the various services have not yet booted. More improvements are are coming in 11.0.0
.