> under 21 ft away, at which distance a knife is as dangerous as a gun.

No, it is not as dangerous.

To use gun from 7 meters away, you have throw it, which takes way more movement hand movement and time. While you should not rely on it, it is very feasible to just move out of the way of the thrown knife.

Other possibility getting closer to you. Running will take 2 seconds. (Not a lot, but definitely not as dangerous as a handgun)

The statistic isn't related to thrown weapons. It's how quickly you can close the space between you and your adversary, as well as how much bearing drift you can create as you do so.