"Fuel" sounded volatile. Why not vent it through the thrusters as additional boost?
Indeed, it could be vented through the thrusters (providing a little bit extra thrust in normal operation, but if the thrusters are down,
it could work nicely as an emergency propulsion method).
In short :
Boiling up the H2 fuel to cool the ship acts as a weak heat sink and provide a thruster mini-boost that reaches 50% of the ship max speed (i.e. blue zone).
It works even with broken thrusters (emergency thrust) and if the ship speed is above 50% (blue zone) it does nothing to the ship speed.