While I completely agree with your assessment that more Americans need to take home security more seriously, no amount of guns, physical fitness, or defensive training could have prevented this horrific incident. The article describes the man being beaten in his sleep, lapsing in-and-out of consciousness while tied up, and losing a lot of blood. There's no way in hell he (or any man) had a chance of fighting off the attackers or even making it to his gun stash alive.
Insinuating that this tragedy could have been prevented is quite insulting. Shit happens, even to the most logical and prepared.