Just get a big enough gun and carry a knife too.
They both have advantages and disadvantages. If we make a fairly apples to apples comparison of an NAA to a knife (i.e. close range in a SD situation where you deploy the item within touching distance), here is how I would break it down:
Ease of use:
The knife can be used with zero training (I know...) and still hurt the bad guy. The NAA requires some training or practice to use.
The nod goes to the knife.
Risk of unintentional injury:
I would argue it's approximately equally easy to cut one's own fingers, and shoot one's own fingers, with the knife or NAA, respectively. However, if we consider the way "most" people use a gun at close range, there is more risk of unintentional injury to innocent bystanders, etc.
Slight safety nod to the knife.
Ability to do damage:
The argument can be made that .22LR to the occipital cavity or to center mass, vital organs, is a fight stopper, and it is. However, the ability to make precision shots follows a bell curve - extreme close distance makes it very hard to make precision shots, as does extreme long distance, with any gun. Likelihood of getting the fight stopping shot at close range is close to zero. On the other hand the knife is really unlikely to stop the fight quickly at all, but has a much greater lifespan of use in the fight. The NAA has a limited number of shots but in a tangle the knife keeps devastating. And while the NAA can be muzzle-averted, it's very difficult to deflect repeat knife jabs or stabs.
Nod goes to the knife.
Finally it's important to consider carry options. I am not aware of a way to carry a NAA mini that is:
-Reliable and consistent to the same degree an OWB knife sheath or OWB or IWB gun holster is
-Safe for use under stress at close quarters (I mean, look at the things... you want to fish in your pocket for THAT when someone's kicking your head in? and the neck holsters should be awarded "worst 'tactical' idea ever")
-Fast (it's small and fumble-prone no matter how you cut it, and hard to reconcile with tactics, techniques, and procedures (TTP) that also work for safe handling of full-sized guns)
Nod goes to the knife