This is a complete stab in the dark - guess work only.
Could it be the extra speed and slow rotation is purely for "passenger comfort" or a smooth/smoother ride? The extra speed and slow rotation would surely enable the aircraft to "ease" into the air. This negates the high angle of attack of a 'normal' lift off and also allows the landing gear to extend nice and slowly which stops the big bump when they bottom out. While this technique is not the most efficient in terms of best rotation speed / initial climb performance, unlike airline ops, the taxpayer is filling the gas tank and the extra fuel burn/inefficiency is of no concern I'm sure.
Like I said - complete guesswork!
Maybe they had a tail wind?
