Guns have hosts of failure modes, and require specialized knowledge on their operation to ensure safety. Guns can even fire accidentally, with an accidental discharge on dropping the firearm being a possibility on any gun without a firing pin block (which is practically any long gun, the kind you can buy at Walmart in some states, with no waiting period in some states). A poorly handled gun may shoot in a totally unpredictable trajectory, and a first time user would be unlikely to consider collateral damage. (Nursery behind the attacker?)
A knife mishandled usually leads to non-life-threatening self-injury. A knife can be dropped, but will only damage those around it that are wearing inappropriate footwear. A knife has very few mechanisms, and only has as many mechanical failure modes as there are gimmicks on the knife; with some having zero mechanical failure modes possible besides faults that are metallurgical in nature. A knife can be wielded poorly with zero training; a first time gun user may never find the safety without assistance, let alone loading and reloading. A knife results in very low collateral damage.
Basically : I'd rather put a limiter on a novice in combat than give him or her weapons in which they put themselves and their family in even greater danger by their own naivety. With proper training, a gun will be the best choice; my personal problem with that decision is that I've met very few properly trained gun enthusiasts that treat firearms with the respect they need to be handled with, and that's not to say I know very few of them.