The answer given is correct but there is an occasion when the SP (showing the ball in the hand) does not actually start the game. If his fatigue percentage is showing in red (not blue), and therefore well below his 'Auto Rest' percentage, the Sim will use the next guy in the rotation.
Two options assuming the indicated pitcher is still going to take the mound:
(a) set the Target and Max Pitch Counts to 20 & 20 (minimum allowed for a SP) and his Pull to 5 - he will probably just get through the first innings before being removed. Downside to this is that the bullpen will end up with a lot of fatigued pitchers so you may be worse off for the next few games.
(b) you can change the guy's position in the rotation - move to the lowest (he will still have the ball). Make him a Tandem A (also the 20/20 & 5) at whatever number it is and then select, say, your LongA reliever and make him Tandem B with a higher than usual set of Pitch Counts and a Pull of 1. That way only one of the bullpen gets crippled for a few days.
Thinking aloud, I wonder what the HBD Sim does if between being given the next start and the game taking place the SP is released (as that is an instant transaction)?