because you had too much fun in playing, what was painful for others
or because during the morning toilet someone came to an idea to nerf it,
or because someone was bored and nerfed this just accidently,
or because it was not nerfed yet, and the task is to nerf everything,
or...
I think it's because the Civilian shuttle is more of a LF/HF hybrid. It has the agility and stats of a LF, but the armament of a HF (class 7 and 8 guns). So that's why the ship has 350m/s cruise speed.