Eh, much ado ‘bout nothing. They never run those tanks dry. They always include an extra 700# of LiH to ensure rich MECO based on low oxidizer levels.
OTOH, if its the oxidizer sensors that are the one’s fritzing, that could be a problem (don’t want to be cavitating those pumps at 35,000 RPM). Bad.
They should just hover their fingers over the engine kill switch, and if the engines don’t cut off when they should just hit the button. How hard can it be?
They did something similar for Apollo 13 for the main engine burn around the backside of the moon.
That’s essentially the flight rationale. They never run the tanks dry (they can’t) and they always “waste” a little bit of propellant. But it would be disastrous if they do run a tank dry. Essentially the backup plan is to manually monitor propellant usage and back-calculate how much is left on the fly. Very worst case there will be an underspeed and they won’t be able to reach the ISS.