Turning downwind with 74 k climb speed meant our ground speed went from 14 to 134 knots. No acceleration applied to the airframe or pilot, as any accelerometer on the aircraft would tell you
Total rubbish, as the document that you link to explains.
Since the INS works by measuring accelerations, in the example you quote, if there was no acceleration when you turn downwind then the INS would instantly be lost.
Im sorry, but this is basic Newtonian physics (again as the document you link to explains) which you learn at school when you are about 14 years old (in the UK anyway). But I'll let you off, because you aren't that old are you?