Fit for duty and not properly assigned rest are different things. If you become ill at 1 hour prior to SC, then what? Bad sushi etc. Just say I was never notified of a 30 hour rest and calculate the legality. You might be ok for a quick out and back or they may have to assign rest properly, which is not the fault of the pilot. They created the default long call system and they must manage rest accordingly. In the poster's scenario when/if they assign a SC they will notice the rest deficiency.