Concours 77
A very plausible scenario except that in all the millions of hours these aircraft have flown since, no one has experienced this problem in the way you describe it. I am sure that there have been many occasions where the boost pumps were deactivated due to a fault or intentionally, but none of these events resulted in a crash due to loss of aileron control.
A very good attempt at building a scenario to fit the presumed radio transmission.