A brand new, completely stock strike fighter has 1440 shields and 1450 hull. Burst cannons at point blank range do upwards of 1000 damage per shot. If you're getting two shot, you're probably also eating a cluster in that timeframe, which is another 882 damage.
GSF is fast paced. Lots of kills are made in a second and a half (generously). Don't give your opponents that big a window of opportunity unless you're 100% positive you can get the kill first.
Don't forget that hitting F1 weakens your shields... I think that they made it +20% damage (down from +30%) and -10% from engine speed and shields, so there is 144 shields gone before he even got shot.