Look, simple fact is that playing games increases physiological indicators of aggression - increased heart rate, etc. But practically any activity that has an element of risk - real or perceived - that induces even a quasi-fight-or-flight response will do the same. Why? Because aggressive behaviours are what allow us to survive harsh circumstances. It's human nature.
In short, this is bullshit. It is NOT the government's responsibility to dictate what folks can or cannot view (exceptions to depiction of real crime, ie rape, murder or peadophilia) - their concern is running the country. It is the PARENTS who must take responsibility for the media their children consume. My parents did, with both of them working full days, so the usual excuse of "Oh, I don't have time" doesn't hold up - they're your damn children, you fucking MAKE time.