By his example plays, RR is telling us that the only time the clock starts on the RFP signal is when the offended team accepts both the distance and time-subtraction penalties. In this scenario, the offended team is obviously wanting to consume as much time as possible.
If they accept the distance penalty, but decline the time-subtraction, then the clock stars on the snap, as well. That makes sense, because the reason they would decline the time subtraction is to conserve time, and starting the clock on the snap further conserves time.
If they decline the yardage, then the time-subtraction is declined by rule, and the game clock starts on the snap. I guess that follows the same concept, i.e., the offended team doesn't necessarily want time to run off the clock, otherwise, they'd accept the distance and time-subtraction penalties.
Le's don't forget - this rule only applies in the final minute of the 2nd and 4th periods.