This sounds rather like a circular and obtuse justification for anything. How could these facts of a liberal democracy suggest that it is best to have people armed? If anything, the only way you could even begin to place the importance of the people to be armed, is to require all citizens to be equally armed. At the moment, only those who are most paranoid and relatively extreme are holding weapons. People like the David Koresh's will always take better advantage of gun ownership over those who either don't choose to have weapons or cannot afford to stock them away as such.
It is wrong to assume that most who are armed are paranoid and/or extreme. And it is best to have people armed because liberal democracies are fragile things.