The idiot let his attention wander in a prison. That in itself should tell you he has no right to even BE a prison guard. This might be in a minimum security prison or something, but the article doesn't specify, so let's take for example a maximum security prison. Instead of the prisoners simply escaping, they could've just as easily slit his throat or strangled him. 5 prisoners, desperate and with the element of surprise, can kill very quickly and very quietly.
Is Plants vs Zombies really worth losing your life over? Ask yourself that question, and if you say yes, ask yourself again. If you still say yes, turn yourself into the nearest mental hospital/gaming addicts anonymous seminar.