This is well and truly unbelievable. Flight directors, whatever they show, were never meant to be followed during rotation. At least not on any aircraft I have flown. Once the aircraft is off the ground, you either follow the FDs if their indications make any sense - or, if they don't or are missing altogether, you pitch for an attitude which gives you more or less the correct climb speed, get away from the ground and sort it out whenever safely possible.
Also, that would have made for a great sim scenario. The PM calls "Rotate", no reaction from the PF.