the unfortunate pilot had no control over them and he will be castigated at the enquiry.
Whilst I agree that skydivers
can be ill-disciplined thrillseekers/andrenaline junkies, the bottom line is that it is the pilot's responsibility to enforce discipline on the aircraft he is in command of. If people are larking about, don't take off or land immediately and read them the rules.
Unfortunately what often happens is that the pilot goes along with the larking about, getting into the spirit of the thing as it were, and takes his or her eye off the ball for a second or two... which is all it takes.
Of course if the jumpers were properly restrained for takeoff... CG properly calculated, even if done on a "standard" loadsheet... well they would all be alive.