I still don't see the problem. First off, there was never any indication that this would be semi-automatic, full automatic, or even magazine fed blaster. The 12/16 gram co2 blasters I plan to make are all bolt action (some magazine fed, some single feed). Second, I don't see what is unfair about it. If it does fire 100 feet with insane rate of fire, there is no guarantee that it will be accurate fire. One accurate, well placed, well timed shoot will beat 18 shoots going all over the place.
Even if the shoots for this high rate of fire air blaster are accurate and has 100 foot range, it is not a game changer. There are plenty of pump action homemades that boast 120 foot ranges and are just as accurate. There are vast numbers of example where accurate slow rate of fire beat out higher numbers of full automatic fire. And those stories are not the exceptions, they are the common place.
What you are saying is that if I played a stock war with stock darts (where all ranges and accuracy are equal) that all the nerf elite styrfes, stockades, rayvens, and rapidstrikes are OP compared to the elite rampage, alpha trooper, and retaliators. And that is simply not true.
It's highly unlikely that an NIC war host will allow a CO2 powered blaster, regardless of what other things you do to sabotage it's effectiveness. In general, the unspoken rule is that you can't carry the stored energy onto the field--you have to put it in the blaster during the game. This presents a physical game balancing factor regarding refire rate, range, and ergonomics. Batteries are a flagrant violation of that rule, but no one really cares because no one has ever made a competitive battery powered blaster.
In addition, single-primed blasters (like most springers) have a safety factor in that no dart will ever be given more energy than the nerfer provides in a single hand motion. Barring visibly obvious workarounds like a foot loop or a hand crank (or whatever the fuck the ultimator does), spring powered blasters are never going to provide drastically more energy than what we are expecting, nor can they ever store and catastrophically release more than a single shot's worth of energy
Sure, there are pump-action springers that shoot 120 feet NIC flat (about 20 degrees from actual flat). But, they are usually huge, poorly balanced (usually front-heavy), and a bit difficult to prime. The plunger movement adds a significant recoil, which combined with typical barrel placement / support, degrades functional accuracy. A CO2 powered blaster will have none of these problems unless you deliberately add them.
Finally, the NIC community has always been anti-CO2 for the aforementioned reasons among others, so even if you did something about all of those things, you're still dealing with an attitude that CO2 is scary and evil. Years of contrary experience with actually safe and fair blasters could slowly change that attitude, but discussion of a hypothetical blaster won't.