That workout doesn’t seem to indicate much faster than the 50.0s that have already been run— to me it looks like the workout of a runner who should be happy with a 49-flat (run with a 23-mid opening split and a 25-mid closing split). And that’s not really taking the tailwind in the workout into account.
That being said, some runners are more racers than they are workout warriors (an admirable trait), and the circumstances those two 50.0s were run in could indicate that for this runner.
This is all a long way of saying I have no idea what this indicates (even in the 400–and I have even less idea what this workout predicts for an 800!)? Best of luck to your runner—I hope they blast like a 47-low and a 1:50!