There a couple of interesting takeaways from this incident. 

1. That it happened in the first place. A private citizen, facing gun, went hands on to disarm and take the gun away and use it. He is not doing that from across the room. He must be attached at some point. 
2. That ii was against two attackers. One of the great criticisms of grappling for self-defense that gets trotted out like clockwork from so-called experts is that grappling leaves you more vulnerable when you are not one on one. But what we see in the real world over and over again is that once one bad guy is facing violence back one them, any other bad guy very often heads for the highway. Obviously, this is not something we can assume will happen, but to assume the exact opposite – that all attackers are looking to engage in gladiatorial combat and will price the fight no matter what – is just as foolish. If we throw out highly functional strategies just because they do not work 100% will leave us with exactly zero options, because nothing works at 100%. Ever.