The difference, in my mind, is that for depth you can pack as much as you can fit anyway, since the increasing water pressure will push your lungs back to normal in a matter of seconds.
But for static, try to pack absolutely full, to the painful treshold, and hold it in for 8 minutes...Not pleasant.
Where as pack absolutely full, exhale some, and after a few minutes inhale it again...That's a totally different story.
So in depth diciplines, the EQEX just gives you a bigger mouthfill and a faster dive reflex.
In static, it would actually allow you to take more air than you would without it...
So if it is to be allowed, it should be obvious that it's allowed only for depth diciplines..
While we're at it, let's ban masks for static
In general I'd like to think that the more extra equipment needed, the less "free" the diving is. But then again, who cares. In the case of no-limits, you already have more equipment then your hard core tech diver, what's a little empty balloon more...