<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by the scribbler:
There is much for Z/V inventory available than G/? as far as I know. I recently had a sitch where I wanted to get rid of an expiring NAMU and tried to use it JFK-LAX and the G waitlist was closed while there were 7 Z seats available.</font>
I think you are confusing the booking codes here.
Upgrades using certs/miles: G/Z
Upgrades using MSUs: V/X
So your post should read: There is more V/X inventory available than G/Z.
And yes, the waitlist for G/Z can be closed while there is V/X inventory avaiable. G/Z can be used by anyone, V/X are elite upgrades only.