Based on his description his modules were shut down immediately after goid interdiction, and he then he was dead.Why?
If you were in faoff prior to entering hyperspace then you will be in faoff after interdiction and goids shut down your modules during interdiction so you will be drifting away cold.
If he jumps faon from zero speed via a boost, then after interdiction as soon as his ship 'reboots' it will throttle down to zero, I wanted to avoid that.
So I recommended jumping with faoff and a boost (after he aligned his ship faon) under the assumption he would be drifting after the interdiction at the speed he had prior to jumping.
Then I tested it and it turns out my assumption is not correct. You will be drifting in faoff after interdiction, which is good, but it seems the speed is set to the same value regardless (70m/s for my chief).
Still, I think he died because he might have been interdicted by a Basilisk so unlikely he can outrun it (unless he is hauling in a clipper or phantom or orca).
So in retrospect depending on which going interdicts you might have to respond differently. For the Basilisk, you should boost away, flip around, pop a heatsink (if you have it) or go silent running and boost towards the Basilisk. If you do it right by the time it turns around you might be able to jump in a slower ship.