I am not comparing it to a game but to WWII. The reason I compare it to WWII is because you have two propeller driven aircraft using guns.
I see no reasons to pull Gs as the aircraft was flying straight & level, fear is not an acceptable excuse. And why would you be afraid of an aircraft that is unarmed. You mentioned that he never fired a shot in anger, what would anger have anything to do with it? You are assigned a mission, why would you be angry?
What makes you think I just fly sims? Certainly I never shot anyone down, but trust me I do a lot more than sims.
First off, look at the video that aircraft was anything BUT straight and level. That country side is hilly and I bet you he was going up and down a couple of hundred feet while doing sharp s-turns.
Second these pilots probably do not have much training in close air combat, so this is their training on the job so to speak. MOST WWII pilots were terrible shots, have you seen combat video from WWII? Most shots are actually missing, and by a lot too. WWII pilots were good, but only a few were as good as your thinking.
Third, as being broadcast over frequency the T27 was having a hard time keeping up with the aircraft, which adds difficulty to the situation at hand.
From what I heard they got the aircraft down in ~7 miles from first engagement, which is quite ok.