I justify it the same way I would justify a 30-06. They are a high powered rifle that falls within the legal definition of arms. I admit, they are at the upper edge of that definition but within none the less.
The fact is that they are expensive and not generally within the pervue of guns commonly used in crimes. In fact, I'm not aware of any ever used in crimes????
I'm far more concerned about Lorcin .22s being straw purchased for distribution to city folks who cannot legally buy a gun because they have caused themselves to be prohibited from owning weapons.
From a practical side as a cop. I've seized numerous pistols of every stripe from criminals. Second most common is the 12ga pump shotgun, usually the cheapest model available. Crooks rarely carry high end weaponry and even when AKs were cheap they were exceedingly rare on the streets. I have never once even encountered or seized an SkS. Thus, if we were going to define criteria for potential real danger on the basis of size, we can see that smaller is more dangerous, not larger.
Now, I know this is just a mental exercise, but perhaps if we could find a way to deal with the bad people problem, rather than the " bad gun " problem, we would actually make some sort of progress.